MOSASATJEID^]. 261 



Suborder PYTHONOMORPHA. 



Body much elongated. Skull of a Yaranoid type, with united 

 nasals and premaxillse, loosely articulated quadrates, teeth on the 

 pterygoids, and frequently sclerotic ossifications 1 . Teeth large, 

 sharp, and anchylosed by expanded bases to the summits of the 

 jaws. Vertebrae with or without zygosphenes, and those of the 

 cervical region in some cases exceeding nine. There is no sternum 

 or clavicle, and usually no interclavicle 2 or sacrum. Limbs in the 

 form of paddles, with the terminal phalangeals devoid of claws, and 

 no foramen to the humerus ; pelvis imperfectly developed. No 

 dermal scutes, at least in most forms 3 . 



Family MOSASAUEIDaE. 



With the exception of Plioplatecarpus, Dollo 4 , all the forms may 

 be included in this family. 



Genus MOSASAURUS, Conybeare 5 . 



Premaxillse not produced into an edentulous rostrum ; teeth smooth, 

 curved, more or less faceted and slightly compressed ; pterygoids 

 not uniting in the middle line e . Vertebrae without zygosphenes ; 

 centra short ; chevrons in the middle and posterior caudal region 

 anchylosed to vertebrae. 



Mosasaurus camperi, Meyer 7 . 



Syn. Mosasaurus belgicus, Holl 8 . 



Mosasaurus hofmanni, auctorum 9 . 

 Mosasaurus giganteus, Cope 10 . 



1 Dollo suggests that these are absentia Hainosaurus ; see Bull. Mus. R. 

 Hist. Nat. Belg. vol. iv. p. 31 (1885). 



2 Present in Plioplatecarpus. 



3 Marsh has referred scutes to some of the American forms ; but the 

 association is doubted by Cope. 



4 See Ann. Soc. Sci. Bruxelles, 1885, pp. 334, 335. 



5 In Cuvier's 'Ossemens Fossiles,' 2nd ed. vol. v. pt. 2, p. 338 (1824). 



G United in Pterycollasaurics, Dollo, Bull. Mus. E. Hist. Nat. Belg. vol. i. 

 p. 61 (1882). 



7 ' Palseologica,' p. 113 (1832). 



8 ' Handbuch der Petrefactenkunde,' pt. i. p. S4 (182'.)). Inappropriate, as 

 Maastricht is now in Holland. 



9 This name is quoted by Mantell in Trans. Q-eol. Soc. ser. 2, vol. Iii. p. 207 

 (1829), where it is applied to Mosasauroid remains from, the English Chalk. 



10 Trans. Amer. Phil. Soc. vol. xiv. p. 189 (1870) ; ex Monitor giganteus in 

 Holl's ' Petrefactenkunde,' op. cit. 



