Also a small p. 303, pl. 17. figs. 5-7). Large, very common. 50. Operculina complanata, Defrance, sp. (1822, Lenticulites complanata, Dict. Sci. Nat. vol. xxv. p. 453). Medium size, rare. This thick Operculina, common in the Red Sea, Indian Ocean, and Australia, is not the typical O. complanata, but rather an intermediate form, showing the close relationship to Nummulina planulata. 51. Operculina granulosa, Leymerie (1846, Mém. Soc. Géol. France, sér. 2, vol. i. Mém. no. 8, p. 359, pl. 13. fig. 12, a-c). Not uncommon. 52. Nummulina planulata, Lamarck, sp. (Lenticulites planulata, Lamarck, 1804; Ann. Mus. p. 187. no. 1). Medium, rare. When at Cagliari in 1871, I obtained a small quantity of the foraminiferous sand found in the neighbourhood of the port from the Director of the Museum. This I also forwarded to Mr. Brady, who quite recently sent me the following list. Cagliari Foraminifera. Biloculina ringens, Lamarck. Rare. Quinqueloculina seminulum, Linné. Common. Also some of the subvarietal forms, such as T. triangularis, D'Orb., and the like. secans, D'Orbigny. Common, specimens very large. subrotunda, Montagu. Rare. Spiroloculina limbata, D'Orbigny. Somewhat rare. excavata, D'Orbigny. Somewhat rare. Nubecularia lucifuga, Defrance. Very common. Peneroplis pertusus, Forskål. Common. arietinus, Batsch. Rare. Orbitolites complanata, Lamarck. Common, specimens small. Cristellaria crepidula, Fichtel & Moll. Rare. Polymorphina gibba, D'Orbigny. Rare. compressa, D'Orbigny. Rare. communis, D'Orbigny. Rare. Textularia sagittula, Defrance. Common. agglutinans, D'Orbigny. Less common. Discorbina globularis, D'Orbigny. Somewhat common, specimens fine. rosacea, D'Orbigny. Rare. Planorbulina mediterranensis, D'Orbigny. Very common. Truncatulina lobatula, Walker & Jacob. Common. Truncatulina refulgens, Montfort. Rare. tuberosa, Fichtel & Moll. Common-the form named by D'Orbigny Tr. variabilis, of which Soldani gives no less than 284 figures in the Testaceographia,' the better to illustrate its wonderful range of variation. Pulvinulina concentrica, Parker & Jones. Rare. vermiculata, D'Orbigny. Very common. Rotalia Beccarii, Linné. Common, specimens large. Polytrema miniaceum, Linné. Common, some of the specimens growing on Nubecularia. Nonionina asterizans, Fichtel & Moll. Rare. depressula, Walker & Jacob. Rare. Polystomella crispa, Linné. Common. IV. On the close Relationship of Hydractinia, Parkeria, and Stromatopora; with Descriptions of new Species of the former, both Recent and Fossil. By H. J. CARTER, F.R.S. &c. [Plate VIII.] IN LIMINE, it may be observed that an intimate knowledge of the structure of the skeleton of Hydractinia is absolutely necessary to trace the chain of resemblances that exists between it and Stromatopora through Parkeria, not less a perusal of the facts as they are consecutively given in this contribution, and, if possible, the presence of the objects themselves. Having had to study carefully the horny chitinous skeleton, which is the most imperishable part of the Hydractiniidæ, in order to write and illustrate a paper on several recent species (Ann. & Mag. Nat. Hist. 1873, vol. xi. p. 1, pl. i.), I am not the less able to see the resemblance that exists between them and those of bygone ages whose skeletons alone are handed down to us in a lapidified state; and hence it was announced that Parkeria had been inferred to be one of these (Ann. & Mag. Nat. Hist. 1876, vol. xviii. p. 187). I was not aware then that species of Stromatopora, even as far back as the Devonian and Silurian systems respectively, would have to fall into the same category; so what I have to state of these will appear in the sequel. All who have studied Parkeria must be aware that it has been well described and illustrated by Dr. Carpenter (Phil. Trans. 1870, vol. 159. pt. 2, p. 721, pls. 72-76); next to which follows Loftusia, equally well described and illustrated by Mr. H. B. Brady (ibid. pls. 77–80). Influenced, however, by the presence of the "primordial chamber-cone" figured by Dr. Carpenter in pl. 72, c1-c4, and pl. 73, fig. 2, ll, I was induced to observe, in the short " Note on Parkeria," added to my paper on the Polytremata (Ann. & Mag. Nat. Hist. 1876, vol. xvii. p. 208), that it could be hardly doubted that Parkeria was a species of Foraminifera, but that "one of the chief characters of the Foraminifera,' viz. the "foraminated area of which the so-called 'nummuline tubulation' is an example," had not been demonstrated. The chief object, however, of this "Note" was to state that the fibre of which Parkeria was composed was not ceous," and that the structure of Parkeria was not identical with the "labyrinthic structure" of the foraminiferal test Lituola nautiloidea, Lam., var. canariensis, D'Orb. arena Up to this time I was under the impression that Parkeria had been a species of Foraminifera; for I had only one specimen myself, in which I could see all that had been described by Dr. Carpenter excepting the "primordial chamber-cone." Subsequently, however, I began to doubt the Foraminiferal nature of Parkeria; and, the nucleus of my specimen in shape presenting exteriorly the pointed end of a Belemnite, which extended from one side of the sphere to the other, I began to think that it had been a sponge which had grown round the end of a Belemnite. But what sponge? was the next question. Luffaria seemed to be the only genus that in fibroreticulated horny structure, when fossilized, would come near to that of Parkeria; and so for some time I, from the presence of this great foreign nucleus, abandoned the Foraminiferal for the Spongial view, still not heartily, till June last, when, my friend Mr. W. J. Sollas having given me some more specimens of Parkeria obtained from the Upper Greensand of Cambridge, amongst which was an entirely uninfiltrated central portion about inch in diameter that, on fracturing the circumferential or hard infiltrated part when the specimen was entire, had fallen like a nut out of its shell, I abandoned both these views, as will be seen hereafter. This nuclear portion also had been so broken as to expose the centre, on one side of which is a small circular or ellipsoidal cavity that appears to have originally contained the object on which the organism had commenced its growth (Pl. VIII. fig. 13, c). Seeing, then, that Parkeria grew upon a foreign body which was on one side of the centre, I also felt satisfied that no Foraminiferous test, either recent or fossil, with which I was acquainted, presented either the fibro-reticulated structure of Parkeria or possessed a foreign body for a point d'appui to grow upon. This decided, I returned to the sponge theory, which again was not satisfactory, as the fibre of Luffaria, which of all other spongeous ones comes nearest in structure to that of Parkeria, is hollow, and not solid as in the recent Hydractiniidæ that I had described in the 'Annals' of 1873 (l. c.); and recognizing the identity in form between the fossilized fibre of Parkeria and the recent fibre of the Hydractiniidæ, especially of Chitina ericopsis, in which some of the stems are an inch in diameter, and the whole bush-like skeleton, branches, hydrothecæ, and every thing else elaborated out of a mass of uniformly anastomosing, reticulated, chitinous fibre without core or cortex, I immediately inferred that Parkeria had been closely allied to, if not a species of Hydractinia. Still to further confirm the inference, I examined the specimens of Parkeria and Loftusia at the British Museum, and those of Parkeria and Hydractinia pliocena (Allman) at the Museum of the Royal School of Mines, through the kind aid respectively of Messrs. H. Woodward and E. T. Newton; after which I obtained an excellent specimen of Hydractinia pliocena from Mr. Ed. Charlesworth, of the Strand, to which I must now add specimens of a recent calcareous Hydractinia from Cape Palmas, on the Guinea coast of Africa, that were sent to me some time ago by my friend Mr. T. Higgin, of Liverpool. Thus prepared for tracing the resemblance of the recent Hydractiniidæ through the fossil species H. pliocena to Parkeria, and thence to the Stromatopora-it is desirable that I should premise a description of the development of the chitinous-fibred skeleton of H. echinata, as well as that of the skeleton or polypidom of the calcareous species from Cape Palmas, in order that I may be the better able to illustrate the fossilized from the recent structure. But as the development of the former has already been represented in the Annals (1. c.), I must refer the reader to the figures there given for this part of my communication. Beginning with Hydractinia echinata, and taking for examination a portion of the earliest or first-formed layer (which will be henceforth termed "lamina ") of the skeleton as it exists on the inner side of a Buccinum bearing this Hydrozoon, where it is almost immeasurably thin, but may be obtained by dissolving away the shell with acid and floating the lamina on to the surface of a slide, for placing it under the microscopeit may be observed, when viewed with an inch compound power, to consist of a branched, anastomosing, cœnosarcal stolon-tubulation, forming a network in which the interstices are filled up with structureless sarcode to complete the membrane. After this, chitinous points (the "horn-cells," see 'Annals,' l. c.) make their appearance irrespectively throughout the membrane so constituted; and these sending out processes more or less sexradiately, which unite with each other, thus form, with additionally superimposed laminæ, the chitinous reticulation of which the skeleton of Hydractinia echinata is finally composed (Ann. & Mag. Nat. Hist. l. c. pl. i. fig. 6). When the reticulation has been thus commenced on the first or basal lamina (Pl. VIII. fig. 1, a), the upper arms of the sexradiate points or "horn-cells" respectively, which are now free, grow into short conical serrated spines (fig. 1, e, e); and thus the surface of the Hydractinia presents an area of such spines, with minute but variable intervals between them, interrupted only here and there by much larger ones of a similar form (fig. 1,g). The same process takes place during the evolution of a second or superimposed lamina (fig. 1, c); but here for the most part the descending arms of the "horn-cells respectively unite with the conical serrated or ascending ones of the first lamina; while the opposite or free arms respectively again assume the short conical form, to remain free, or unite in like manner with the descending arms of a third lamina (fig. 1,ƒ). We have now three laminæ (fig. 1, a, c, f), and therefore two intervals or interlaminal spaces (fig. 1, b, d), beyond which the chitinous skeleton of Hydractinia echinata seldom extends. In both instances the two intervals are converted into pillared cavities respectively by the union of the ascending and descending arms of the horn-cells respectively; but the upper interval is much wider than the lower one, and therefore the reticular spaces thus formed much larger. On examining the surface of each lamina separately, it may be further observed that many of the short conical serrated spines of the first lamina are not met by corresponding descending points of the second one, and therefore remain free (fig. 1, e, e) in the lower interval. This does not appear so often in the upper interval, while, of course, on the surface of the third or last lamina, which is that of the surface of the skeleton of the Hydractinia itself, they are all free (fig. 1,ƒ). Although differing slightly in height, they average about inch, which is twenty times less than that of the large spines (fig. 1, g), to which I have above alluded; but while they consist, for the most part, of solid points respectively, the structure of the large spines is more or less reticular, as will now be particularly explained. |