VARANIANS. 263 



pressed sub-recurved crown, with a trenchant anterior and posterior 

 edge, which hkewise presents a fine and close dentation. In the best 

 preserved cranial fragment of this reptile, (which is now in the 

 British Museum) , fourteen or fifteen of these teeth may be counted in 

 the left upper maxillary bone ; and a fragment, apparently belonging 

 to the same jaw, exhibits three additional teeth : the posterior of 

 these teeth, which, extend below the orbit, are smaller than the rest. 

 The fragment of the premandibular bone contains five teeth. 



The crown of the teeth is covered by a coat of remarkably 

 smooth and polished enamel, which presents the same brown tint as 

 that of the glossopetrse or fossil shark's teeth. Soemmering conjec- 

 tured that the Geosaurus might be a young individual of the Mosa- 

 saurus, but Cuvier justly observes that the teeth of the Mosasaurus 

 differ from these of the Geosaurus in their greater breadth, especially 

 from side to side ; and in the non-dentated character of the ridges 

 which divide the internal convex from the external flattened side of 

 the crown. 



The form of the vertebrae of the Geosaurus indicates its near 

 affinity to the crocodilian group, and the Argenton fossil crocodile 

 presents the same subcompressed teeth with dentated trenchant 

 margins, as does the Geosaurus. 



VARANIANS. 



109. The Varanian family of squamate Saurians, which includes the 

 Monitors of the old world, and in which some of the species approach 

 nearest in size to the Crocodiles, manifests its affinity to that group 

 in the absence of pterygoid teeth, and in the number of successive 

 tooth- germs which may be observed at the same time behind the 

 fixed and functional teeth. (1) Besides these characters the Varanians 

 must excite our interest from exhibiting in some species a form of 

 tooth which most nearly resembles that which characterizes the 

 Megalosaurus and other very remarkable extinct terrestrial species of 

 gigantic squamate Saurians. 



In a small species of extinct Lizard, referable to the present 

 family, from the gault and chalk-formations, the teeth were awl- 



(1) PL 63 A, fig. 9, Varanus variegaius. 



