I 



CETACEA. 





M 



at thin point between the lachrymal and the jugal bones. A little 

 lower down, in a depramion, is pieroed the hrge suborbital hole, which 

 U thai carried farther backward than the edge of the orbit, and cannot 

 ire place to any canal The dental part of the maxillary a more 

 inward than the orbit, so that the interior part of the wall of 

 thin cavity it formed by a flat advancement of that bone. The zygo- 

 matic apophyau of the temporal bone is thicker than in any other 

 animal, but the rest of the bone is moderate ; it contributes to form 

 the aidei of the occipital cnwt, and leaven above, between it and the 

 superior and lateral occipital*, a space which permita the petrous bone 

 to be seen. The two creata which limit the temporal fossa above run 

 in a nearly parallel direction, and do not unite in a single line, as in 

 the greater part of the C'anu'roro. In the adult there is only a single 

 unequal parietal bone, which enters largely into the temple ; but in 

 the foetus there are two, completely separated by a double inter- 

 parietal ; these four bones however speedily unite, not only with each 

 other, but, what is singular, with the upper occipital, even before the 

 other parts of the occipital are united. The plane of the occipital is 

 inclined from before backwards, and from above downwards, and the 

 occipital crest makes an obtuse angle ; there is no vestige of a mastoid 

 apophysis. Below, the intermaxillaries form the point of the muzzle, 

 occupying nearly the fourth of the palate, and surrounding a large 

 incixive hole, which is single, because they have no internal apophyais. 

 Very young Manatees have a small tooth in each of their intenuaxil- 

 laries, thus completing, Cuvier observes, their analogy with the Dugougs. 

 He observed this in the f ictus, but he remarks that the tooth disappears 

 at a very early period. The jaws commence a little behind the sub- 

 orbital hole, which, from the disposition of the orbits, is found nearly 

 at their level. The palatine bones advance in a narrow and obtuse 

 point, occupying nearly a fourth of the palate, and contribute to the 

 formation of two large pterygoid wings, whose body is in other 

 respects almost entirely sphenoidal, and does not separate itself from 

 the body of the posterior sphenoid even in the foetus. The temporal 

 ate of the sphenoid remain distinct much longer. The palatine bone 

 shows itoelf in the temple by a narrow tongue-shaped process, between 

 the maxillary on one side and the anterior sphenoid and the frontal 

 on the other ; but its continuity is partially hidden by the dental 

 portion of the maxillary bone, which is continued backwards to the 

 wing of the sphenoid, which it touches without articulation. The 

 anterior sphenoid also only shows itself in the temple by a narrow 

 tongue-shaped process, but much shorter than that of the palatine. 

 It does not reach the parietal bone, and the orbital wing of the sphenoid 



Skull of Manatee AJtanalia auttralii). 



touches the frontal The body of the baailary bone and that of the two 

 sphenoids are conjoined with each other and with the cribriform plate 

 of the ethmoidal bone, considerably before the basilary unites with 



nearly flat sufaces, as in all the Ilerbivora. The ascending ramus is 

 very wide, and its posterior angle rounded. The caronoid apophysis is 

 directed forwards, and truncated nearly into a hatchet-sha|>e. The 

 region of the symphysis is thick and elongated anteriorly. The whole 

 portion that supports the gum is perforated with small holes. The 

 holes for the exit of the lower maxillary are very large. The lateral 

 and dental portions of the lower jaw are very large and rounded. 



The shoulder-blade U 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. It* 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 backwards. The ulna and radius, which are 

 rather short in proportion to their stoutness, and still more so with 

 reference to the size of the animal, are joined together by their two 

 extremities. Their upper articulation corresponds to the pulley of 

 the Immurus ; 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 Jferbirora. 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 trap<v.oi<l 

 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 those 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 seizing 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 tho 

 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 possess but little mobility. 



There are only 6 cervical vertebra?, all very short. The annular 

 portion of the third, the fourth, and the fifth is incomplete. Tho 

 transverse apophyses of the fourth, fifth, and sixth are pierced with a 

 hole ; they are all simple. There are 16 ribs and 16 dorsal vertebra; ; 

 the spinous apophyses 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 

 vertebra; may be called lumbar, and then there would be 22 caudal 

 Thus there are in all 46 vertebra;. Under the joint of the first eleven 

 caudal vertebra; are articulated small chevron bones, as- in the greater 

 part of quadrupeds which have a powerful tail The transverse 

 apophyses of the vertebra; of the tail are very large, especially in t In- 

 first, but the spinous processes are inconsiderable; which accords, 



Skeleton of Manatee (ifanattu auitralit). 



the lateral occipital*. 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 iU 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. The 

 criata gall! is prolonged more backwards than they are. There U no 

 nella ; the whole base is united ; the median fosatc hardly depressed. 

 The analogous hole of the xpheno-palatine is large, and entirely in the 

 palatine bone. The optical foramen is small and in the form of a 

 canal ; the sphcno-orbital, which comprises also the rotundum, is 

 rather large and of an oval form : the foramen ovule 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 n 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 tl. 

 as convex internally as externally. 



The connections of the bones of the skull of the. Dugong, Ac. arc, 

 r 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 intermaxillary bones to make 

 room for the tusks, and to curve the symphysis of the lower jnw 

 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 t!i:.t :mim>il. 

 In a word, says Cuvier, one might say that a Manatee is only a 

 Dugong whose tusks are not developed. 



