8 OBSERVATIONS UPON 



nassiers and the carnivorous marsupials. In the common 

 seal we find a simple tubercle at the maxillary angle ; in the 

 Phoca cristata this process is more obtuse ; and in the Pho- 

 ca leptonyx, de Blainville, it is quite obsolete. 



We see indeed that this process re-appears and becomes a 

 character of more importance in the genus Otaria, in which 

 it constitutes a strong, trihedral projection, obtuse, and pro- 

 longed into a prominent ridge below the jaw. But there is 

 one characteristic mark in the species of this genus, which 

 quite removes all affinity to the fossil jaw; — their molar teeth 

 have but a single root. 



Thus the supposed Didelphis does not appear to be refera- 

 ble to the family of the seals. 



A.s we never see this angular process disappear in the car- 

 nassiers, I think we may therefore conclude that the fossil 

 bones found at Stonesfield belong to a terrestrial carnivorous 

 mammal ; and on account of the great number of its teeth, 

 that it is more closely related to the didelphs than to any other 

 known mammiferous animal. 



The present investigation furnishes a fresh proof that the 

 attentive study of even the smallest parts of organic struc- 

 ture leads to very curious general results, since they become 

 characters, the importance of which we did not in the least 

 anticipate. 



The prolonged tongue-shaped process is absent in man, in 

 the Quadrumana, and in the frugivorous bats, animals in 

 which the articulation of the jaw does not require that fixed- 

 ness which is a necessary condition in the existence of the 

 carnassiers. This process in the last furnishes a strong in- 

 sertion for the ligaments or sets of muscles which regulate 

 the lateral movements of the jaw; when it closes, they fix it 

 in its articulation, and produce that action of the teeth neces- 

 sary for the proper mastication of the food. This process is 

 obsolete, or nearly so, in those seals which are placed in the 

 order carnassiers, because these seize their prey in the water, 

 and transfix it with their pointed teeth rather than masticate 

 it, and do not therefore require so much fixedness of articu- 

 lation. 



If we observe it to become projecting among the Otarice, it 

 is easy to account for this by a simple examination of their 

 slightly pointed teeth, inserted obliquely and across the den- 

 tal arch, and which would have been less fitted for retaining 

 living prey, if the lower jaw had been capable of making a 

 lateral movement below the upper one. 



Were I not afraid of wandering from my subject, it would 

 be easy for me to demonstrate that the prolongation of the 



