102 THE SEA-HORSE. 



shape of the upper jaw depends upon the sockets, 

 which receive the great tusks, and remind us of the 

 Elephant. It will also be noticed, that the lower 

 jaw shuts in between these tusks, and so rests upon 

 the upper one. The great sockets are placed be- 

 tween the nostrils and the orbit, the rim of which 

 is wanting for nearly one-third of its circumference. 

 The cranium itself is not large ; but its processes 

 are well marked, serving for the insertion of the 

 powerful muscles which move the head. The posi- 

 tion of the grinders, and their shape, are here also 

 seen, four on each side of each jaw, which, with the 

 two tusks, makes eighteen in all ; the grinders are 

 small. Cuvier adds, that between the tusks are 

 two incisors, shaped like molars, which the genera- 

 lity of writers have not yet recognised to be inci- 

 sors ; between these again are two small and pointed 

 ones in young individuals.* 



* In the preceding volume of the Naturalist's Library, (Mam. 

 v. 7th,) our friend Mr MacGillivray having supplied, from the 

 cranium of a young Walrus, in the Museum of the Royal College 

 of Surgeons, the first published description of the normal denti- 

 tion of this animal, we subjoin it. In the skull of the young, 

 there are in the upper jaw three incisors on each side; the first 

 or inner extremely small, the second a little larger, and the third 

 or outer disproportionately large, being equal to the largest 

 grinders. The canine tooth is displaced, being thrust outwards 

 beyond the line of the other teeth ; there are then five grinders, 

 with single roots, the fifth very small. In the lower jaw there 

 are two very small incisors on each side, the canine is wanting, 

 and five grinders. In adults, the incisors are obliterated, except 

 the lateral pair of the upper jaw; the fifth grinder also disappears, 

 and sometimes the fourth. 



