ROOM III. VERTEBRAE OF MOSASAURUS. 199 



teeth anchylosed to the alveolar ridge of the mandibular 

 bone, have been discovered; and assuming the probability 

 that these jaws, teeth and vertebrae, of the Mosasaurian 

 type belonged to the same genus, but differed specifically 

 from the Maestricht animal, Mr. Charlesworth proposed to 

 distinguish it provisionally by the name of Mosasaurus 

 stenodon. 



To resume. The jaw of the Maestricht animal is three 

 feet nine inches in length ; the entire length of the skeleton 

 is estimated at twenty-four feet ; thus the head is nearly one- 

 sixth of the total length a proportion according with that 

 of the crocodiles, but differing from the monitors. The tail 

 is only ten feet long, and therefore but half that of the 

 total length ; while in the crocodile the tail exceeds the entire 

 length of the body by one-seventh ; its shortness is owing to 

 the abbreviation of the bodies of the vertebrae. 



This animal formed an intermediate link between the tribe 

 of saurians without pterygoidal teeth, the monitors, and 

 those with them, the iguanas : its only approach to the cro- 

 codiles was in a few partial characters, and in those general 

 bonds of connexion which re-unite the entire family of 

 oviparous quadrupeds. The bones of the extremities are but 

 imperfectly known ; those attributed to the Mosasaurus are 

 said to indicate members adapted for natation rather than 

 for progression on land, and to support the inference of 

 M. Cuvier, that the original was a marine animal of great 

 strength and activity, having a large vertically expanded tail, 

 capable of being moved laterally with such force as to consti- 

 tute a powerful instrument of progression, capable of stemming 

 the most agitated waters. 1 



Teeth in every respect analogous to those of the Maestricht 

 reptile were discovered by Dr. Harlan of Philadelphia, from 

 the equivalent deposits of the cretaceous formation, the 



1 In the Memoir of M. Adrien Camper, " Sur quelques parties moins 

 connues du squelette des Sauriens Fossiles de Maestricht," there are 

 figures of several metacarpal or metatarsal bones from Maestricht, which 

 the author describes as resembling those of the Crocodile, and probably 

 belonging to the great saurian ; among them is a small conical shaped 

 bone, termed an ungual phalanx, but which has more the character of 

 a dermal tubercle or spine ; the figure, however, is too small and inde- 

 finite to show the true nature of the original. 



