LACERTILIA. 307 



partial anchylosis to depressions on the inner side of an 

 alveolar wall, or according to the " plenrodont type." Their 

 enamelled crowns are moderately long, compressed, pointed, 

 slightly recurved, with a well-marked but finely serrated 

 margin before and behind ; the thickest part of the crown is 

 not at the middle, but nearer the anterior border, as in the 

 great Yaranns (Var. crocodilinus) and in Megalosaurus ; and 

 they resemble, in miniature, the teeth of that great carnivo- 

 rous reptile. To the question whether these Purbeck fossils 

 might not be of a foetus or young of the Megalosaurus, the 

 answer is, that the lower jaw of the ISTuthetes differs from that 

 of the Megalosaurus in not having the inner alveolar wall 

 produced in a greater degree than in the modern Varani, and 

 in not exhibiting any rudiments of alveolar divisions. The 

 largest teeth measure two lines in diameter at the base of the 

 crown, the length of the largest fragment of the mandible was 

 one inch and a half; the depth of the outer wall was six 

 lines, that of the inner wall was from three to four lines. 



The fossils give evidence of a carnivorous or insectivorous 

 lizard of the size of the Varanus crocodilinus, or great land 

 monitor of India. The specific name relates to the adapta- 

 tions of the teeth for piercing, cutting, and lacerating the prey. 



A smaller kind of lizard, from the same formation (Sau- 

 rillus obtusus* Ow.), is chiefly represented by the right dentary 

 element of the lower jaw containing thirteen teeth. These 

 are moderately long, conical, and obtuse ; and are neither so 

 long nor so recurved as in Xuthetes. On the outer side of the 

 dentary bone, not far below the alveolar border, are six nervo- 

 vascular foramina in a longitudinal row, relatively as numerous 

 and large as in the Iguanodon, and indicating, as in that and 

 other Saurian reptiles, the scaly covering of the jaws and the 

 equally reptilian simple and subdivided condition of the sali- 



* Abbreviation of saurns, a lizard. Quarterly Journal of the Geological 

 Society, No. 40, pp. 423 and 482. 



