404 LOWER VERTEBRATES. 



co.ists of New Jersey and Alabama, as well as the " Western Sea." It contains the 

 most elongate forms of the order, though they do not reach such a size as do some of 

 the JLiodotis. The quadrate bone gives evidence that there was considerable lateral 

 flexure of the mandibular rami ; and that the animals were strong and muscular is 

 shown by the striations and sculptures still appearing on many of the bones. That 

 the vertebral column might not be dislocated by the animal's powerful contortions, the 

 vertebriB are provided with an extra pair of articular processes which are very charac- 

 teristic. The largest representative is C cineriarum, from the Kansas strata, and 

 reaches a length of forty feet. C. tortor was a lithe and active animal, with numerous 

 knife-like teeth, and probably fed on fish. C. pumilus is remarkable for its small size, 

 being only about twelve feet in length. It was jirobably not infrequently the unfor- 

 tunate prey of some of the larger cretaceous sharks. 



The genus Platecarpus is also represented by about a dozen species which resemble 

 Clidastes in the form of the humerus, though the vertebral articulations are like 

 those of Liodon. The muzzle is considerably shorter than in the previous genus, 

 from which the animals also differ in having the chevron-bones free from the vertebral 

 centra. The teeth are very characteristic, being neither compressed like Liodon, nor 

 angularly faceted as in Mosasaurus but are curved and, in section, sub-circular. 

 Such specimens as have been discovered have been of medium size. 



Fig. 234. — Skeletpn of Clidasles, restore.I. 



Mosasaurus has been abundantly found in the greensand of New .lersey, and other 

 cretaceous localities further south. It differed from the two previous genera in having 

 the flippers more pedunculate, the humerus and femur being more slender, and in 

 having the teeth provided with facets. The chevron-bones are in part coossified, and 

 the arches of the vertebral column interlock, presenting in rudiment, the articular 

 processes of Clidastes. The representatives of tliis genus, of which there were in 

 Europe two, and in America, where the animals were much more abundant, nearly a 

 dozen species were, like other Pythonomorphs, long and slender, and with a flattened, 

 pointed head. The food, which was captured .alive, w.as quickly swallowed, passing, 

 on its way to the loose pouch-like gullet, between the expanded branches of the lower 

 jaw. J£ via.vi7)uis was the largest species, and sometimes reached a length of eighty 

 feet. 



The genus Liodon has the teeth compressed, lenticular in sectional outline, and 

 formed for cutting. The vertebrjB have not the strong articular processes of Clidastes 

 and the humerus is small and narrow. The tyjjical sjiecies of the genus was described 

 by Owen from remains found in the*English chalk, and is extremely rare. In America 

 the forms abounded during the chalk period and were the giants of the order. L. 

 proriffcr, of the Kansas beds, measured seventy-five feet in length, and was provided 

 with a long projecting muzzle, a development possibly used as a ram when fighting. 

 L. di/spelor was ])robably the largest of known reptiles, considerably exceeding the 

 Mosasaurus maximus in size. The source of the food sujiply of such monsters may 

 well excite our curiosity, as their magnitude does our surj)rise. 



