The alionlder-blade is nearly semi elliptical ; its lower line being almost straight, and answering to the great axis of the ellipse : the spine occupies only the anterior half of the bone. Its greatest pro jection is near its root; it is prolonged forwards into a pointed acromion, which ascends a little obliquely, and which has the air of terminating by an articular facet. There are no clavicles. A strong blunt tubercle occupies the place of the coracoid process. The humeral surface is a little higher than it is wide, and very concave. The upper part of the humerus is also very convex ; its external tuberosity is very projecting. The bicipital groove is not deep, but there remains a deep canal between the internal tuberosity and the articular head; the deltoidean crest is but little marked. The lower head is a rather oblique simple pulley, ascending at the internal edge. Its width is not greater than its antero-posterior diameter. The internal condyle projects much more than the other backward& The ulna and radius, which are rather short in proportion to their stoutness, and still more so with reference to the size the animal, are joined together by their two extremities. Their upper articulation corresponds to the pulley of the humerus; the head of the radius is wider than it is high, and, even when not conjoined, is incapable of executing rotation ; in which circumstance the Manatee differs still more widely from the Seals, to approximate itself to the Herbirora. The radius has below, at its external surface, two pointed crests. There are only six carpal bones ; the pisiform bone is wanting, and the trapezium and trapezoid are united into a single bone, which is articulated at once with the metacarpal bone of the thumb and of the fore finger. The analogue of the os magnum responds to thorn of the fore and middle fingers. The unciform bone responds to the middle, ring, and little fingers, which last articulates itself at the same time with the cuneiform bone of the first row. Each of these bones has also in the Manatee its particular character. The pisiform bone, Cuvier observes, is also wanting in the Dolphins, and is very small in the Seals and Sloths, whilst it is very long in the animals which make much use of their fore feet for ecizing or progression. The metacarpal bones are flat above and carinated below ; that of the thumb, which has no pha langes to support, terminates in a point ; the others are enlarged at their lower extremity. That of the little finger is longer and the most enlarged of all. The ring-finger, on the contrary, is that which has the longest phalanges; but those of the little finger are flatter and wider. All the articular surfaces of the phalanges are rather full, and must podess hut little mobility.
There are only 6 cervical vertebne, all very short. The annular portion of the third, the fourth, and the fifth is incomplete. The transverse apophyses of the fourth, fifth, and sixth are pierced with a hole ; they are all simple. There are 16 ribs and 16 dorsal vertebrze ; the spinous apophyscs of which last are moderately elevated and inclined backwards. Counting from the sixth dorsal, there is on the ventral surface of their body a small sharp crest The two succeeding vertehrx may be called lumbar, and then there would be 22 caudal. Thus there are in all 46 vertebrae. Under the joint of the first eleven caudal vertebrae are articulated small chevron bones, a.v in the greater part of quadrupeds which have a powerful tail. Tho transverse apophyses of the vertebne of the tail are very large, especially in tho first, but the spinoue processes are inconsiderable; .which accords, the lateral occipitala. The area of the section of the cranium is nearly half of that of the face ; it is singularly high, especially before, In proportion to its length. The frontal bones are there nearly vertical ; the cribriform plates are found below the anterior surface ; they are small, not much pierced with holes, and scarcely sunk. Tho crista galli is prolonged more backwards than they are. There is no
sells ; the whole base is united ; the median foam hardly depressed. The analogous hole of the spheno-palatine is large, and entirely in the palatine bone. The optical foramen is small and In the form of a canal ; the spheno-orbital, which comprises also the rotundum, is rather large and of an oval form ; the foramen ovals is a notch of the border of the posterior sphenoid, completed by the tympacic bone ; the condyloidean is very small, and in the form of a notch of the lateral occipitaL The articulation of the lower aw is formed by Cuvier remarks, with the depressed form of the tail-fin, to prove that the Manatee swims by a vertical movement of the tail. The ribs are singularly stout and thick ; their two edges are rounded, and they ere as convex internally as externally.
The connections of the bones of the skull of the Dugong, 47C. aro, Cuvicr observes, nearly the same as in the Manatee. To change, he adds, the head of the latter to that of the Dugong, it would suffice to render more convex and elongate the intermaxihlary bones to make room for the tusks, and to curve the aymphysis of the lower jaw downwards so as to make it conform to the inflection of the upper jaw. The muzzle would then assume the form that it has in the Dugong, and the nostrils would be raised as they are in that animal. In a word, says Cuvier, one might say that a Manatee is only a Dugong whose tusks are not developed.
The enormous development of the intermaxillary bones of the Dugong carries up the aperture of the bony nostrils much higher than in the Manatee, and it is situated at the superior part of the head in the middle of its length and directed upwards, its form being a large oval as in the Manatee of Senegal. The whole skull, and particularly the frontal bones, are for the same reason much shorter in proportion than in the Manatee. The branches of the frontal bone which form the upper part of the orbit are more delicate and more rugose. The maxillary portion which serves as a floor for the orbit is narrower ; the jugal bone in turning to form the anterior and inferior edge of the orbit is more compressed and directed more downwards. There is also a lachrymal bone in the anterior angle more considerable than in the Manatee, but equally without any hole. The zygomatic apophysis of the temporal bone is more delicate and more compressed. The connections of the bones of the cranium are the same, but at the inferior surface the basilary bone is united with the lateral occipitals rather than with the posterior sphenoid. A very great solution of continuity is seen in the bottom of the orbit and of the temple, and establishes in the skeleton an extensive communication between these two fosses and that of the nostrils ; it is intercepted between the maxillary, the frontal, the anterior sphenoid, and the palatine bones. The continuity of the temporal portion of the palatine with the rest of the bone is not here concealed, as in the Manatee, by a production of the maxillary bone. The occiput is narrower and its crest less marked than in the Manatee ; the frame of the tympanum is also narrower and more delicate, but the bone of the ear is disposed nearly in the same way, and is let in between the same bones. There also remains in the skeleton a large empty space between that bone, the basilary, and the anterior sphenoid. Within the cranium there is no bony tentorium ; the cribriform foasa is reduced to two simple depressions very much separated from each other, and which terminate anteriorly by two or three small holes. There is no cella Turcica. The optic aperture is a long narrow canal.. The lower jaw is of a two long slender bones, which have some resemblance in form to the clavicles of man. There are V-shaped bones articulated under the interval of the vertebra after that which comes beyond the pelvis. They diminish by degrees, and seem to terminate altogether under the last fourth of the tail.