122 



low large animals wliole, but arc not furnished at the same time with tlie 

 arrangement of the suspensorium, the quadrate, and mandible, by which they 

 unfold downward, thus increasing the vertical diameter of the pharyngeal 

 cavity. The palatine and maxillary arches not having the mobility seen in 

 snakes, the mandibles possess increased adaptation to the necessities of doubt- 

 less similar habits. 



The accompanying cut shows the appearance of the normal flexure of 

 the ramus: c is the splenial articulation ; d, the coronoid process; and e, the 

 quadrate cotylus. 



Fig. 4. — Right inaiulibiilar ramus of CUdastcs pvojxjthon, Coiic, ouc-thiril natural size : a, from tbo 

 inner side; fc, from above. Fig. .5. — Left ramus of ioxocmiMs htcoloi; a pjtbouid from Central America, 

 inner side, uatural size. Fig. 6. — Riglit ramus of liryx johuii, Euss., from India, inner side, natural sizo; 

 1, articular; 2, surangular; 3, angular; 4, corouoid; 5, splenial; G, deutary. 



Vertcbrcc and ribs. 



Vertebra. — As has been already pointed out l)y Cuvier, the vertebra} in 

 Mosasaurus flill into cervical, dorsal, sacro-lumbar, and caudal series. The 

 cervicals are either round or depressed ; they are arbitrarily characterized by 

 the presence of an obtuse hypapophysis, which has an articular surface for a 

 separate continuation of the same. The latter may be compared to short, 

 compressed, ungueal phalanges. The articular extremity of some is nearly 

 plane; of others, conic, with antero-posterior enlargement. They are directed 

 posteriorly, and have a broad, obliquely ovate outline on the lateral view. 

 Their extremities are rugose. 



The atlas consists of the three pieces, the l)asal and two lateral. The 

 axis supports a large odontoid proces*;, which is bounded below by a three- 

 sided piece, which is provisionally called its hypai)ophysis. Besides these, 

 he axis has its own (jroper fixed and corresponding free liypapophyses. 



