and the shortness of its coronoid process as compared with the condyloid. It bears, however, a not distant likeness to the lower jaw of the insectivorous Macroscelides typicus, which has also a short coronoid.

EAR. Our animal would appear, like the desman and the mole, to be devoid of an external ear, but this is not the case. True, there is no pinna, and the concha is represented only by a delicate cup-like ring of cartilage surrounding the aural orifice immediately behind the eye. But on removing the integument. a very singular auditory apparatus is displayed in the form of a long winding osseous tube, commencing where the bony meatus generally ends, ascending behind the articulation of the jaw, arching over the root of the zygoma, and then running horizontally to the point where the modified conchal orifice opens close to the tiny eye. This winding tube, however, is not in a single piece, but in two; the first of which is connected by cartilage with the short canal (the true bony meatus, not a quarter line in length) leading from the tympanic ‘bulla,' and extends to a length of three lines, terminating at a point opposite the junction of the temporal, parietal and frontal bones. At this point it is joined by an interposed ring of cartilage to the second piece, only one line in length. This singular acoustic tube is capable of limited movement, and is furnished with a delicate muscle attached to the temporal bone near the root of the zygoma. The tympanic bulla, just mentioned, is in fact the tympanum itself, developed external to the cranium. It occupies the ordinary position of the mastoid process, consists of an ovoid, bubble-like, thin-walled chamber of considerable capacity-separated from the meatus by a true membrana tympani-and contains the usual chain of ossicles connecting that membrane with the fenestra ovalis. On its lower and inner aspect this bulla is somewhat contracted, and is pierced immediately behind the pterygoid plate by a minute orifice leading into the eustachian tube. Το revert to the osseous tube connecting the tympanum with the concha, I would observe that it is evidently the homologue of the cartilaginous meatus auditorius, elongated and ossified to meet a special requirement. The nearest approach to this remarkable development is in the Echidna, whose external

auditory meatus is composed of a long series of cartilaginous rings. Resolve these rings into two bony tubes, and you have the organ of the Chlamydophorus.

The OLFACTORY organ has also a special development; for in addition to the usual surface afforded by the nasal fossæ and the ethmoidal cells, the two remarkable frontal tuberosities consist of an intricate labyrinth of cells, which freely communicate with the latter.

Hence it will be seen that although the organ of vision is so inconspicuous as to have earned for the animal the name of Pichi-ciégo, or 'blind armadillo'—the deficient sight is abundantly compensated by the extraordinary provision made for smell and hearing.

The Scapula attracts notice on several accounts. 1. From its general contour: the superior margin is convex, the inferior concave, and the anterior straight, while the posterior angle curves downward to a sharp point like a pruning-hook. In Dasypus the anterior and superior margins are convex, and the inferior straight, while the posterior angle points directly backwards. 2. In Chlamydophorus the dorsum is divided into three nearly equal portions by two spines' or crests, the upper of which supports the enormously long hooked acromion, and the inferior, not quite so elevated, terminates at the neck of the scapula. The space between the lower spine and the angle affords a broad origin for the powerful triceps muscle. 3. The acromion process, which is equal in length to the spine from which it springs, takes so wide a sweep as to overhang the greater tuberosity of the humerus; thus affording increased leverage to that bone, and while protecting the joint anteriorly, enlarges its cavity; this renders necessary the interposition of a synovial bursa. A similar arrangement occurs in Orycteropus.

The Sternum presents one or two features worthy of note. It is composed of six bones, of which the first (manubrium) is much the largest, for the support of the broad articulation of the plate-like first rib. This bone and the next (first mesosternal) have a sharp crest or keel along their anterior surface—

1 As in cholapus and myrmecophaga, and some S. American simiada. 2 Prof. Hyrtl, p. 23.

a vestige of bird-like structure which is seen in a less degree in Cholapus and Dasypus, and in the 'interclavicle' of Ornithorhynchus1; but in Chlamydophorus this feature is proportionally more ornithic than in either of these. The next three pieces are small, like flattened beads connected by cartilage, thus serving, together with the articulated ribs (another birdlike element) to compensate for the want of expansibility, owing to the complete ossification of the latter. The xiphisternum is separated from the fifth piece by the dovetailing-in of the conjoined plates of the 6th, 7th, and 8th ribs on either side.

But by far the most striking anomaly in the skeleton before us is the singular pelvic shield, to which Hyrtl has given the name 'sphæroma ischii.' As his description is quite exhaustive, I cannot do better than transcribe it. He begins by exclaiming with pardonable enthusiasm: "Inusitata, vel, ut rectius dicam, inaudita plane pelvis conformatio, verum prodigium osteologicum est, cui per omne mammalium regnum, nihil simile datur aut secundum."

He then proceeds: "The unusual characters (of the pelvis) consist, first, in the pubis being open in front, as in birds; and secondly, in the mutual growing together (mutuo coalitu) of the enormous tuberosities of the ischium, whence is developed the truly miraculous bony shield, which for the future it will be convenient to call the Sphæroma ischii.

"The pelvis, elongated as in the Dasypi, is composed of the sacrum and innominate bones, whose symphyses degenerate into true synostoses. The number of the sacral vertebræ, on account of their intimate union, can only be estimated by the number of inferior sacral foramina, which, since there is some asymmetry in the anterior region of the pelvis, appear to be ten. The first three coalesce with the iliac bones-the last four blend with the ischia-the three middle contract no union with either of these bones, but constitute the upper margin of the ischiadic foramen. Thus far it tallies in the strictest sense with Dasypus gymnurus (Xenurus, Rapp). But now appears a notable difference. From the dorsum of the sacrum arise three longi

1 Parker's Monograph on Structure and Development of Shoulder-Girdle, p. 193.

tudinal crests, of which the median absorbs the lateral ones, so that behind the great ischiadic foramen only one crest remains, which, in the shape of a slender, pellucid, and much-perforated lamina, is produced throughout the length of the sacrum, and posteriorly amalgamates with the sphæroma. This median crest, at the spot where, by the accession of the lateral ones, it receives an increase of substance, is evolved into a dense transverse lamina, which is associated on either margin with a long and unusual process of the ischium that I denominate the ascending. By this means a double canal is formed, whose arch is the transverse lamina just described--whose base is the dorsum of the sacrum-whose external wall is the ascending process of the ischium, and whose internal wall is the median crest itself which separates the two canals. These ample canals we will call c. suprasacrales majores. Nor is this all. From the dorsal aspect of the transverse lamina are sent out, in a backward and upward direction, two strong rounded bony columns, which, diverging from each other, impinge upon the sphæroma and become as many props to it. It is evident that between these columns and the median crest, there are two canals also, similar to those already described. These we name the c. suprasacrales minores."

In the adult D. gymnurus, the innominate bone consists, as usual, of three bones which are joined by interposed cartilage. But in Chlamydophorus they form a genuine synostosis.

The ilia surmount the sides of the anterior sacral vertebræ, with which they are united, in the shape of wings, and afford an ample surface for the origin of the dorsal muscles. The ischiadic notch is converted into a true foramen.

The ischium is united to the sides of the posterior sacral vertebræ, and possesses three rami, of which the superior is the 'ascending process' above named; the second, directed downwards and forwards, meets the os pubis, with which it unites to form the lower boundary of the obturator foramen; the third, remarkable for its strength and breadth, affords the sturdiest support to the sphæroma ischii, into which it is inserted.

The os pubis is distinguished from the ilium by the presence of a broadish ilio-pubic tubercle. It consists of only one ramus which is joined to the descending ramus of the ischium,

and closes the obturator foramen. With its fellow of the opposite side it has no connection, and hence, in the bony pelvis, there is a gap below of six lines in width'. In place of a symphysis, however, there is an arch of fibro-cartilage projected forwards which closes the pubes, and receives the fibres of the recti abdominis muscles. In Xenurus (according to Hyrtl) the symphysis is closed, not by the continuous development of the pubic bones, but by the interposition of a small wedge-like bone on either side of the median line. Similar cuneate bones are said to occur in D. sexcinctus, but not in D. novemcinctus", where the normal ossification is complete. This is a very interesting developmental link.

This marvellous Sphæroma, then, distinctly belongs to, and is part of, the bony pelvis, to which it is united by five fulcra. Of these the two principal, and lowest in situation, arise from the ischium-the two middle are the columns erected on the transverse lamina of the sacral crest-and the highest is the termination of the median crest. Since the main buttresses of the shield occupy the place belonging, in other Dasypods, to the tubera ischii, it seems evident that this anomalous structure is developed from the confluence of the tuberosities. It has no analogy to the cutaneous skeleton which occurs in the form of bony plates in all the Dasypi: for in these animals the bony shields of the skin are never united to the subjacent parts of the skeleton by a true synostosis, as in Chlamydophorus.

In position, the sphæroma is vertical; in shape, it may be compared to a semicircular buckler with its convex margin directed upwards. This margin is thick, rounded, and beautifully crenated with bosses and intermediate fissures, corresponding with the first row of tesseræ in the perpendicular piece of the horny dermal coat which overlies it. The lower margin of the shield is acute, and also crenated, and consists of two nearly straight radii, as it were, converging to the semilunar median notch, which embraces the base of the tail, but without touching it. The anterior surface is concave, but unequal and rough, pierced by many nutrient foramina. The posterior is smooth,

1 This hiatus is greater in proportion than in the Sloths or in the Shrews the only other mammals whose pelves are open anteriorly.

2 Tatusia peba, Desm.