404 , LOWER VERTEBRATES. 



coasts 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 Liodons. 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 

 vertebrae 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 probably 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 sj)ecimens as have been discovered have been of medium size. 



Fig. 234. — Skeleton of Clidastes^ restorefl. 



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



cretaceous localities further south. It differed from the two jirevious 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 this 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, was quickly swallowed, passing, 



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



jaw. M. maxiinus 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 vertebrae have not the strong articular processes of Clidastes 



and the humerus is small and narrow. The typical species 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. 



proriger, 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. 



X. dyspelor was probably the largest of known reptiles, considerably exceeding the 



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



well excite our curiosity, as their magnitude does our surprise. 



