CETACEANS. 351 



in the lower jaw(l). The permanent or mature dentition of the 

 Beluga {Delphinus leucas, Pall.) is more normal though scanty, nine 

 teeth being retained on each side of the upper jaw, and eight in each 

 ramus of the lower jaw ; they present the form of straight, subcom- 

 pressed, obtuse cones. The Delphinus globiceps, which has 5|zi| = 52 

 strong, conical and pointed teeth in the vigour of its age, begins 

 soon after to lose them, and in aged individuals none remain in 

 the upper jaw, and not more than eight or ten are preserved in 

 the lower jaw ; those at the anterior part of the jaws last longest 

 and their summits are received in cavities in the upper jaw, or 

 the gum covering it, when the mouth is shut. 



The most formidable dentition is that of the predaceous Grampus 

 {Phocfsna Orca) whose laniariform teeth are as large in proportion 

 to the length of the jaws, as in the Crocodile ; they are in 

 number J|eJ| = 50, all fixed in deep and distinct sockets, separated 

 by interspaces which admit of the close interlocking of the upper 

 and lower teeth when the mouth is closed. The longest and largest 

 teeth are at the middle of the series, and they gradually decrease 

 in size as they approach the ends, especially the posterior one ; 

 the shortness of the anterior teeth is in great part due to the 

 wearing down of the sharp summits, which are best preserved 

 in the small posterior teeth ; the position of the bruising and 

 piercing teeth being the reverse of what commonly obtains. An 

 analogy to this circumstance in the dentition of the great predatory 

 Dolphin, is however, manifested by the typical carnivorous qua- 

 drupeds in which the incisors are shaped more like grinders than 

 the back teeth. 



In the great or Bottle-nose Dolphin rDelphinus tursioj the 

 teeth are fewer and larger in proportion to its size than in the 

 common Delphinus delphis ; but proportionally less developed and 

 more numerous than in the Grampus, the dental formula being 

 He! = 90 with a variation of three or four more or less in each 

 jaw ; the teeth are conical, sub-obtuse, the posterior ones smaller 

 and sharpest. In the common Dolphin the number of teeth amount 

 to 190, arranged in equal numbers above and below. They have 



(1) Proceedings of the Acad, of Philadelphia, 1842, p. 127. 



