intentional grossness.

Like all professed humorists, he made | occasional mistakes; but he, too, was on the right side in the warfare against the pretentiousness of Cant and the effrontery of Vice, the two master evils of the age and the society in which he lived. The following is a list of Foote's farces or comedies as he calls them, mostly in three, some in two acts, which remain in print. The date of production, and the character originally performed by Foote, are added to the title of each :

The Knights (1748-Hartop, who assumes the character of Sir Penurious Trifle); Taste (1752); The Englishman in Paris (1753Young Buck); The Englishman Returned from Paris (1756-Sir Charles Buck); The Author (1757- Cadwallader); The Minor (1760-Smirk and Mrs Cole); The Liar (1760); The Orators (1762-Lecturer); The Mayor of Garratt (1763-Major Sturgeon) The Patron (1764-Sir Thomas Lofty and Sir Peter Peppercorn) The Commissary (1765-Mr Zac. Fungus); The Devil upon two Sticks (1768-Devil); The Lame Lover (1770-Sir Luke Limp); The Maid of Bath (1771-Mr Flint); The Nabob (1772--Sir Matthew Mite); The Bankrupt (1773-Sir Robert Riscounter); The Cozeners (1774-Mr Aircastle); A Trip to Calais; The Capuchin (1776-O'Donnovan).

Foote's biography may be read in W. ("Conversation") Cooke's Memoirs of Samuel Foote (3 vols., 1805), which contain a large collection of his good things and of anecdotes concerning him, besides two of his previously unpublished occasional pieces (with the act of the Diversions in a later form already mentioned), and an admixture of extraneous matter. From this source seems to have been mainly taken the biographical information in the rather grandiloquent essay on Foote prefixed to "Jon Bee's" useful edition of Foote's Works (3 vols. 1830). But few readers will care to go further than to the essay on Foote, reprinted with additions, from the Quarterly Review, in the late Mr Forster's Biographical Essays; and none can fare better than those who turn to this delightful and discriminating study of a man of real though peculiar genius. (A.W.W.)

FOPPA, VINCENZO, a painter, was born in Brescia soon after 1400, and died there in 1492. He settled in Milan towards 1425, and was the head of a school of painting which subsisted up to the advent of Leonardo da Vinci. His contemporary reputation was very considerable, his merit in perspective and foreshortening being recognized especially. Among his noted works are a fresco in the Brera Gallery, Milan, the Martyrdom of St Sebastian; a Crucifix in the Carrara Gallery, Bergamo, executed in 1455; the Trinity, in the church of S. Pietro in Oliveto, Brescia; and other paintings in the same city.

FORAMINIFERA. This designation is part of that given by D'Orbigny in 1825 to an order of animals forming minute calcareous shells (found recent in shore-sand, and fossil in various Tertiary Limestones), for the most part many-chambered, and often bearing a strong resemblance in form (fig. 1) to those of Nautilus, Orthoceras, and other chambered Cephalopods,-his (supposed) Cephalopoda

poda sipunculifera (Nautilus and its allies) by the want of the "siphon which passes from chamber to chamber in the latter, and its replacement in the former by mere "foramina" in the dividing septa. And it seems to have been the applicability of this term Foraminifera to the shells thus characterized which has caused it to be retained as their ordinary designation, notwithstanding that the knowledge since acquired of the animals that form these shells necessitates the removal of the group from the elevated position assigned to it by D'Orbigny, to nearly the lowest grade of the whole animal series. It was by the admirable observations upon living Foraminifera published by Dujardin, in 1835, that attention was first drawn to the existence of a type of animals more simple than any previously known, their bodies consisting entirely of an apparently homogeneous semi-fluid substance, to which he gave the name sarcode"; and this substance projecting itself through apertures of the shell into indeterminate ramifying extensions (which he termed pseudopodia), capable of being retracted and fused again (so to speak) into the general mass of the body. Regarding these animals as a section of the large group of Infusoria, whose bodies he supposed to have a like simplicity of sarcodic composition,

Triloculina; 4, Biloculina; 5, Peneroplis; 6, Orbiculina (cyclical); 7, Orbiculina (young); 8, Orbiculina (spiral); 9, Lagena; 10, Nodosaria; 11, Cristellaria; 12, Globigerina; 13, Polymorphina; 14, Textularia; 15, Discorbina; 16, Polystomella; 17, Planorbulina; 18, Rotalia; 19, Nonionina.

the simplest type of an animal, designated a Moner (see ANIMAL KINGDOM, vol. ii. p. 50), consists of an independent particle of the elementary form of living matter known as "protoplasm" (the "sarcode" of Dujardin), which is capable of growth and maintenance by the assimilation of nutrient material, and of multiplying itself either by subdivision or by some modification of that process. Now the first stage of differentiation of this apparently homogeneous substance into histogenetic elements consists in the appearance of certain rounded bodies termed endoplasts, which appear to be the equivalents of the nuclei of the "cells" whose indiAnd the viduation marks a higher stage of differentiation. next stage (well seen in Amaba) consists in the differentiation of a more consistent external layer, or " ectosarc," from the less consistent substance of the interior, or endosarc,' in which are observable "vacuoles" containing fluid, of which one or more (that seem bounded by a definite pellicle, and are known as "contractile vesicles") contract and dilate rhythmically. As yet, however, there is no definite point of entrance for alimentary particles, or of exit

for excrementitious matter,-nutrient ingesta being admitted, and their unassimilable residue being got rid of, through any spot of the ectosarc. It is in the presence of a definite mouth, and usually of an anus also, that even the simplest of the true ciliated Infusoria show a decided advance upon the "rhizopodal" type, an advance which is still more marked in the higher Infusoria by the complexity of their internal organization.

Now the animal bodies of Foraminifera, notwithstanding the regularity and complexity of the shells they form, show but a very slight advance on the simplest moneral type. For their protoplasmic substance does not seem to be differentiated into "ectosarc" and "endosarc,"-every part of it alike projecting itself into pseudopodial extensions, and these extensions being capable, not only of dividing and ramifying indefinitely, but also of reuniting by mutual fusion when they come into contact with each other, so as to constitute an irregular network (figs. 2, 3, 4). It is on account of this last peculiarity that the writer has distinguished the reticulose forms of the Rhizopod type from the lobose (consisting of Amaba and its allies) on the one hand, and from the radiolarian (of which Actinophrys is the type) on the other. The sarcodic bodies of Foraminifera were believed until recently to have neither "nuclei " "" nor contractile vesicles"; but as the observa tions of Hertwig and F. E. Schulze have established the presence of these in some instances (the writer also having observed "endoplasts "in Orbitolites), it is probable that they exist universally.

The attention which has been given in recent years to the study of Foraminifera, has invested the group-formerly considered as comparatively insignificant with a new interest and importance. For (1) these minute testaceous Rhizopods, instead of having mere local habitats, are diffused abundantly through all save polar seas, and seem to do the first work of collecting by imbibition, and of converting into living substance, the organic matter which is contained, however sparingly, in all oceanic water, and the restoration of which, as fast as it is thus withdrawn, is effected by the various forms of marine vegetation.1 Again (2), without That all marine animal life must ultimately depend upon marine vegetation is as certain as that all the animal life of the land ultimately depends upon terrestrial vegetation. And looking to the very large proportion which, not only among Fishes, but also in the higher Mollusca, Crustacea, and Echinodermata, the carnivorous bear to the phytophagous types, and to the abundance of the former ou bottoms far too deep for the growth of the Algae required for the sustenance of the latter, and on which there is no raining down" of Diatoms from the surface (as in polar areas), it seems obvious either that there must be animals capable of generating organic compounds for themselves out of the gases contained in ocean-water, or that it must itself supply nutrient material in the liquid form to animals specially adapted to imbibe and assimilate it. Of the possibility of the former hypothesis we have no evidence whatever; and in the absence of light at great depths, any new production of organic compounds seems almost inconceivable. On the other hand, the analyses made by Dr Frankland of the specimens of ocean-water brought home in the " Porcupine" expedition of 1869 have shown that it always contains an appreciable proportion of nitrogenous matter; while in Foraminifera there seems to be a special capability of imbibing and assimilating such matter by the extension of the soft body into a protoplasmic network, exposing a very large surface. Of the importance of this provision (first suggested by Sir Wyville Thomson) in the economy of nature the following is an apt illustration:-Large quantities of cod are taken by fishermen on the Faroe banks, attracted thither by the abundance of star-fish, on which they greedily feed; and the stomachs of these star-fish are found to be filled with Globigerina. Thus man is dependent for this "harvest of the sea"-in the first place upon the star-fish that feed the cod; secondly, on the foraminifers that feed the star-fish; thirdly, on the organic material (in very weak solution) which ocean. water supplies to the foraminifers; and finally, ou the various forms of marine vegetation by which this supply is continually being renewed. The writer deems it probable that the same function is performed by Sponges, whose ramifying internal canal-system provides a vast extent of absorbent surface, and that this is the explanation of the otherwise singular fact, that the "cold-area" (temp. 30° Fahr.), not far from the Faroe banks, swarms with various types of boreal Echinoderms,

any thing that can be called organization, the protoplasmic bodies of these animals give origin to protective casings of marvellous regularity of form, and often of great complexity of structure, these being sometimes "tests" built up by the apposition of sand-grains or other particles collected from the bottom on which they live, the animals only furnishing the cement by which they are held together, but being more often true "shells," formed (like the skeletons of higher animals) by an interstitial deposit of carbonate of lime drawn from the surrounding medium, in the substance of living tissue. Notwithstanding (3) the absence of any perceptible differences in the character of the animals they respectively contain, these protective casings, whether sandy "tests" or calcareous "shells," present a wide diversity of fundamental form, which is almost indefinitely augmented by subordinate modifications; and these modifications are generally so gradational as to render it impossible (when a sufficient number of specimens are compared) to draw any lines of separation between what appear, when only the extremes are regarded, to be clearly differentiated types. And this is true, not merely of species (which in the sense of constantly differentiated races cannot be said to have any existence among Foraminifera), but also of what would elsewhere be accounted genera; whilst even families cannot, as a rule, be sharply defined, many of them containing aberrant forms that defy all attempts at strict limitation. In fact it would be scarcely a figure of speech to say that, within each of the three primary subdivisions of the group to be presently marked out, every form passes gradationally into every other. Hence the study of Foraminifera-whose snall (but not too small) size and numerical abundance are peculiarly favourable to the comparison of large series of individuals-affords a most valuable lesson in taxonomy,—giving the best illustration that the whole animal kingdom can afford of the production of almost endless varieties of conformation by "descent with modification." Looking (4) to the almost universal diffusion of existing Foraminifera, and to the continuous accumulation of their calcareous exuvia over vast areas of the ocean-bottom, there can be little doubt that they are at present doing more than any other tribe of marine animals to separate carbonate of lime from its solution in sea-water, so as to restore to the solid crust of the earth what is being continually withdrawn from it by the solvent action exerted by rain and rivers upon the calcareous material of the upraised land. And when (5) we look back into the past history of our globe, we not only find conclusive proof of the enormous contributions which Foraminifera have made to the calcareous strata of Tertiary and Secondary epochs (Nummulitic Limestone and Chalk having been almost entirely formed by their agency), but encounter strong reason for the belief that the principal mass of the Paleozoic Carboniferous Limestone had a similar origin. And when finally (6) we go still further back in geological time, and bring our knowledge of this type to bear on the very earliest calcareous formation that has yet been found in stratified rocks (the Serpentine Limestone of the Canadian Laurentians), we find distinct evidence that this also had its origin in Foraminiferal growth; which has thus stamped the impress of its existence even upon the oldest of those Archaic rocks, which, through a long subsequent succession, have as yet yielded no other distinct evidence of the existence of either animal or vegetable life on our planet. And thus in all parts of the geological series we not only recognize the constructive work of these humble organisms, but, interpreting the past by the

notwithstanding the almost entire absence of Foraminifera caused by the depression of temperature, their place being taken by a particular type of Sponge which there finds a congenial hubitat, and probably supplies food to higher marine animals.

present, find ever-increasing reason to believe that it has exceeded that of all other marine animals taken collectively. A concise statement of the evidence in support of each of these positions will be embodied in the following sketch of the life-history, present and past, of this group; which will be so drawn as rather to bring into view its great features of general interest, than those details with which the systematist only is concerned.

Although the testaceous Foraminifera are all marine, certain shell-less animals essentially similar in nature occur in fresh water; and these, of which Lieberkühnia (fig. 2)

of vegetable cells) which is constantly going on through the whole protoplasmic network, and the latter becoming enclosed in a kind of sheath formed by the blending of the neighbouring pseudopodia, which apply themselves to its surface and draw it into the central mass by their gradual contraction. Although destitute of any protective envelope, Lieberkühnia does not put forth its pseudopodia indifferently from any part of its surface, their primary stem being enveloped in a transparent sheath, which may be traced as a thin pellicle over the whole body. And in Gromia (fig. 3), of which some forms inhabit fresh water (attaining a size that renders them visible to the naked eye), whilst others are marine, this pellicle is thickened into a distinct casing or "test" of ovoidal shape (probably composed of chitin1), with a single round orifice of moderate size, through which the sarcodic body puts forth its pseudopodial extensions. When the animal is in a state of repose, these are entirely retracted into the test; but when its activity recommences, they are put forth from its orifice, as from the stem of Lieberkühnia, and form a sarcodic network which is in a state of incessant change-new centres of radiation often arising where two or more pseudopodia coalesce, by the flowing of the protoplasm towards those points. It is specially noticeable in this type that the sarcodic body extends itself over the entire surface of the test, so as completely to enclose it, and that pseudopodia are put forth from every part of this extension, being especially numerous at the posterior end, where they probably serve to fix the test, and thus to enable the animal to put forth more power in seizing the larger creatures that serve as its food. For whilst it is partly nourished by the minute granules that adhere to its outspread network, it lays hold of the smaller Infusoria and Diatoms, the zoospores of Confervæ, &c., and draws them entire into the interior of the test, within which their indigestible remains may frequently be seen. Now, if the transparent pellicle of Lieberkühnia were consolidated by calcareous instead of by chitinous deposit, a monothalamous (single-chambered) "shell" would be produced (9 in fig. 1), such as constitutes the permanent form of the simplest Foraminifera, and the primordial form of even the most complex. This shell, like the test of Gromia, may have but a single aperture, from which the pseudopodial extensions are put forth, and through which alone nutriment is received into the contained body. But in a large proportion of the polythalamous (many-chambered) Foraminifera (fig. 4), the shell-wall is perforated with minute pores over its entire surface, through which pseudopodia extend themselves in a radial direction; and while the coalescence of these at their origin forms a continuous sarcodic layer that covers the exterior of the shell, the coalescence of their extremities forms new centres of radiation at a distance from it. The aperture or mouth in these types is much smaller than in the preceding, and appears to serve rather for the projection of the stolon-process, by which new chambers are formed (in the manner to be presently described), than for the introduction of nutriment. And when it is considered that the diameter of the pores of the shell never exceeds 1-5000th of an inch (being often much less than 1-10,000th), and that the chlorophyllgranules, zoospores, &c., that nourish the fresh-water Rhizopods are altogether wanting in the sea-depths inhabited by the higher types of Foraminifera, there seems additional ground for the doctrine already propounded, that the nutrition of the animals of this group is mainly drawn rather from the organic matter that is dissolved in the medium they inhabit, than from solid particles suspended in it.

In regard to the propagation of Foraminifera, little is as yet certainly known. The growth of the individual may proceed, as will be presently shown, to an almost indefinite extent, by the gemmiparous multiplication of the segments or divisions of its body, with a corresponding multiplication of the chambers of its shell; but it more frequently happens that when the organism has attained a

FIG. 4.-Rotalia, with pseudopodia extended through the pores of the shell. certain limited size, the new segments detach themselves, each one growing into the likeness of its parent; and this is probably the ordinary way in which the continuance of the race is provided for. But it would also seem that under certain circumstances the sarcodic body of the parent breaks itself up into segments, each containing an "endoplast" or nucleus," and that around each of these a shelly covering is formed while it is still enclosed within the original shell, the offspring finally escaping by its rupture. Whether this mode of propagation is preceded by any process of "conjugation," and is thus related to sexual generation, is still undetermined.

By far the greater number of Foraminifera are composite fabrics, evolved from a simple protoplasmic body by a process of continuous gemmation, each bud remaining in connexion with the stock from which it was put forth; and according to the plan on which this gemmation takes place, will be the configuration of the composite fabric thereby produced. Thus if the bud be put forth from the aperture of the monothalamous Lagena (9 in fig. 1) in the direction of the axis of its body, if a second chamber be formed around this bud in continuity with the first (receiving the neck of the latter into its own cavity), and if this process be successionally repeated, it is obvious that a straight, rod-like shell (10 in fig. 1) will be produced, having a series of chambers communicating with each other by the apertures that originally constituted their mouths, and opening externally by the mouth or aperture of the last formed chamber. The successive segments may be all of the same size, or nearly so; in which case the entire series may either resemble a string of beads, or may approach the cylindrical form, according to the shape of the chambers. But it more frequently happens that each segment somewhat exceeds its predecessor in size, so that the entire shell has a somewhat conical shape. If, on the other hand, the axis of growth should be slightly curved instead of straight, the resulting composite shell will be arcuate, while a more

rapid deflection gives it a spiral curvature (5 and 11 in fig. 1). The form of the spire will depend in the first place upon whether its convolutions lie in the same plane, like those of a nautilus, so that the shell is equilateral (16 and 19 in fig. 1), or pass obliquely round a vertical axis, as in a snail, so that the shell becomes "inequilateral" (18 in fig. 1), having a more or less conical form, with the primordial chamber at its apex. In other cases, again, the vertical axis is greatly elongated, and the number of chambers forming each revolution around it is reduced to four, three, or even two (13 and 14 in fig. 1). But further, the spiral plan of growth may give place to the cyclical, successive circles of new chambers being formed around the interior growth, so as to give the shell a discoidal shape (6 and 17 in fig. 1). And sometimes all regularity of plan disappears in the later stages of growth, new chambers being added in various directions, so that the fabric becomes "acervuline."

In the older classifications of Foraminifera, these differences of plan of growth were adopted as characters of primary importance in the subdivision of the group. But it has now become obvious that comparatively little value is to be attached to them. For to associate together all rectilineal, all spiral, and all cyclical Foraminifera, is not only to run counter to the indications of natural affinity that are furnished by the intimate structure of the shell, the conformation of the individual chambers, and the mode of their intercommunication, but to set at nought two general facts of fundamental significance,-first, that one plan of growth often graduates insensibly into another, as does the straight into the spiral in the group of which 10 and 11 of fig. 1 are extreme forms; and, second, that it is not at all uncommon for the plan to change during the growth of one and the same individual, the spire, for example, either straightening itself out, so as to revert to the rectilinear type, or returning into itself so as to make a complete circle, round which a succession of concentric annuli is then produced on the cyclical type, while the original regularity is sometimes lost altogether in the "acervuline" piling up of the later-formed chambers. Ou the other hand, the fundamental importance of the perforation or imperforateness of the external envelope, as affecting the physiological condition of the contained animal, is now universally admitted. For where (as in Peneroplis, 5 in fig. 1) that envelope, whether composed of calcareous shell or built up by the cementation of sand-grains, has no other communication with the exterior than by the single or multiple aperture of the last chamber through which the whole pseudopodial apparatus of the contained animal is put forth, the nutrition of the entire segmental body that occupies the previously formed chambers must be carried on by a continual interchange of protoplasmic substance extending through the entire raass, however great may be the multiplication of its segments. Where, on the other hand (as in Rotalia, fig. 4), the wall of each chamber is perforated for the passage of pseudopodia, the segment it contains is thereby placed in direct communication with the surrounding medium from which it derives its sustenauce, so as to be independent of the remainder of the series. The "imperforate" calcareous shells of Foraminifera are also termed "porcellanous," from the opaque-white aspect they present when viewed by reflected light; though, when thin, they show a rich brown hue by transmitted light. Even under a high magnifying power, their substance appears entirely homogeneous. The perforated shells, on the other hand, having an almost glassy transparence (except where this is interrupted by tubulation), are known as "vitreous" or "hyaline." Where the shells are thin, the perforations are simply pores (fig. 4); but where they are thick, the perforations are tubules usually running straight and parallel from surface to surface (fig. 24).

Thus, then, the Foraminifera are naturally divisible in the first instance into two groups, the Imperforata and the Perforata; the former of which is again divisible into the Arenacea, which build up "tests" by the aggregation of sand-grains, and the Porcellanea, which form porcellanous shells; whilst the latter, Vitrea, includes all the perforate types. There is often a very curious parallelism between the forms contained in these three series respectively, still more between certain "porcellanous" and certain "vitreous" types; but this arises in each case from similarity in plan of growth, and does not indicate any real affinity. In fact the two calcareous-shelled series may be compared to two trees of different orders, which resemble each other in their mode of branching, but have dissimilar leaves and flowers. I. ARENACEA. The calcareous shells of certain types of Foraminifera, alike in the "porcellanous" and in the " and in the "vitreous" series, are not unfrequently covered with sandgrains, cemented into the surface-layer of the true shellsubstance. But in the group now to be described, the casing of the body is entirely composed of foreign particles (usually grains of sand, but sometimes minute Foraminifera, sponge-spicules, &c.), the animal furnishing nothing save the cement that holds them together; and in its lowest forms no special cement seems to be supplied, the sandgrains being simply imbedded in the sarcodic substance of the body. The increased attention which has of late been given to this group (our knowledge of which has been. largely augmented by deep-sea dredging) seems to justify our regarding the arenaceous type as on the whole less advanced than either the "porcellanous" or the "vitreous,"its lowest forms presenting a condition less specialized than even the simplest of the calcareous-shelled Foraminifera, whilst its highest, although sometimes attaining a comparatively gigantic size, build up their massive " tests upon a very simple plan, exhibiting no approach to the complexity of structure to be found in the "shells" which some of them closely resemble in external form. A few of the more interesting types of the Arenaceous group will now be briefly noticed.

In the sandy mud which covers certain parts of the bottom of the 500-fathoms channel between the north of Scotland and the Faroes, the large monothalamous Astrorhiza are so abundant as sometimes to form a great part of the contents of the dredge. Their typical shape (as the name implies) is discoidal with stellate radiations but they are sometimes globular, sometimes cervicorn, and present every intermediate gradation between these forms. The "test" is composed of loosely aggregated sand-grains, not held together by any mineral cement; and it is destitute of any definite orifice, so that the sarcode-body (of a dark green colour) which occupies the cavity must put forth its pseudopodial extensions between the sand-grains of its test. But there is, in the writer's belief, a lower form even than this. For in the same dredgings there were found a number of little globular masses varying in size from a pin's head to a large pea, formed of aggregations of sand grains, foraminiferal shells, &c., held together by a tenacious protoplasmic substance, without any definite structural arrangement. And although these might be supposed to be mere accidental agglomerations, yet there seems adequate reason for regarding them as living organisms of the simplest possible "monerozoic" type. For just as a simple moner," by a differentiation of its homogeneous protoplasm, becomes an Amaba, so would one of these undifferentiated mixtures of sand and protoplasm, by the separation of its two components-the sand being limited to the superficial layer, so as to form an investing test,' of which the whole interior is occupied by the sarcode-body alone, become an Astrorhiza.

The next degree of elevation is shown in the presence of a distinct aperture or mouth, the sand-grains surrounding which are generally held together firmly by a ferruginous cement, even when those of the remainder of the test are as loosely aggregated as in Astrorhiza. One of the most common forms of this type is a simple cylindrical tube, closed at one end, but having a conical neck with a circular orifice at the other. And in a still higher type, this cylinder is divided into a succession of chambers, each of which opens into the next by a conical orifice bordered by cemented sand-grains, while the last opens externally by a like orifice,-thus sketching out the "nodosarine" type of the "vitreous" Foraminifera, but on a much larger scale.

In the more advanced Arenaceous types, on the other hand, the sand-grains of the entire "test" are firmly united together by a cement composed of phosphate of iron, which must be exuded from the sarcodic body of the animal, its materials being originally derived from the sea water. In some instances the sand-grains selected are of such minute size that, when worked up with the cement, they form a sort of "plaster," the surface of which is quite smooth, both mina, under which is ranged a whole series of forms ranging from externally and internally. This is the case with the genus Trochama simple undivided tube to a perfect helical spire resembling a Catherine-wheel (whence the name given to the genus), and thence, by the alteration of its spire to the turbinoid, and by the subdivision of its cavity into chambers, to the "rotaline" type. In other instances the sand-grains are somewhat larger, but are apposed with such extraordinary regularity, and cemented together so artificially, as to form a most delicate but firm test of very uniform thickness, perfectly smooth both externally and internally. Tests of this. kind present a singular series of adumbrations of the "orbuline," "globigerine," and "nodosarine" types of the vitreous series. In other cases, again, the sand-grains being larger, the "test" is constructed more coarsely, but still with remarkable symmetry. One of the most interesting of the simple coarse-grained forms is the little Saccammina spherica, whose flask-shaped tests (fig. 5, a, b) of the size

FIG 5.-Arenaceous Foraminifera:-a, exterior of Saccammina; b, the same laid open; c, portion of test more highly magnified; d, Pilulina; e, portion. of test more highly magnified.

of minute seeds, with prolonged necks and circular apertures, now found living abundantly in particular localities, have been also distinctly recognized in Carboniferous Limestone. That the size of the sand-grains used in the construction of such tests is not accidental (depending on the fineness of division of the sandy bottom on which the animals live), but is the result of selection on the part of the animals that use them, is shown not only by the fact that coarsegrained and fine-grained "tests are brought up from the same bottom, but by the very curious difference in the materials used to form two kinds of tests nearly of the same size and of corresponding simplicity of type. The very same deep dredgings which yielded Saccammina brought up a number of other monothalamous spherical tests, filled with dark green sarcode, to which the name Pilulina has been given from their resemblance to homeopathic globules (fig. 5, d). These, instead of being constructed by the cementation of sand-grains, are composed of a sort of felt (e) made by the regular "laying" of siliceous fibres (the fine-pointed ends of elongated sponge spicules) with very minute sand-grains dispersed among them; and the aperture, instead of being a round hole at the end of a short neck, is a sigmoid fissure with somewhat projecting lips. The constancy of these differences indicates a dissimilarity in the " potentialities" of the animals of the respective types, of which we find no indication in their apparently-homogeneous sarcodic bodies.

The highest development of this type known to exist at the present time is shown in the large polythalamous "nautiloid" forms which have been brought up in considerable abundance from depths mostly ranging between 200 and 500 fathoms. The test (fig. 6, a) is for the most part composed of coarse sand-grains firmly cemented to each other; but it is generally smoothed over externally with a kind of "plaster" resembling that of which the "trochammine" tests are made up. On laying open the spire, it is found to be very regularly divided into chambers by partitions formed of cemented sand-grains (b), a communication between these chambers being maintained by a fissure left at the inner margin of the spire. So far, the plan of structure accords with that of the smaller "nonionine" forms (resembling 19 of fig. 1), which are