M0SASATJKID2B. 265 



genus, it will be characterized as follows : — Premaxillae produced 

 into an edentulous rostrum ; teeth (fig. 57) nearly smooth, curved, 

 and more or less compressed, and in the posterior part of the jaws 

 with well-defined fore-and-aft carinse, of which the posterior one 

 may disappear towards the muzzle. Vertebrae short, without zygo- 

 sphenes, and with weak zygapophyses ; chevrons, at least in many 

 cases, free. Humerus long and narrow. 



It should be observed that all the Mosasauroid vertebras from the 

 English Chalk have the chevrons anchylosed to the centra ; but it 

 does not certainly follow that they are referable to L. anzeps. 



Liodoia anceps, Owen \ 



Syn. Mosasaurus stenodon, Charlesworth 2 . 

 (?) Liodon lundgreni, Schroder 3 . 



The type species. Only known by fragments of jaws and de- 

 tached teeth. The latter are much compressed, and indicate an 

 animal much smaller than Mosasaurus camperi. 



Bab. Europe (England, Germany, France, and (?) Sweden). 



The following specimens are from the Upper Chalk. 



48939. The crown of a tooth ; from Norwich. Purchased, 1878. 



48940. A similar specimen ; from Norwich. Same history. 



R. 1227. Cast of the crown of a tooth. The original is from 

 Norwich, and is preserved in the Woodwardian Museum, 

 Cambridge; it is somewhat smaller than No. 48939. 



Made in the Museum, 1888. 



R. 1228. Cast of the crown of a larger tooth. The original is 

 from Norwich, and is in the Woodwardian Museum. 



Same history. 



41639. Fragment of the mandible, with the broken bases of 

 {Fig.) two teeth; from Essex. One of the types. Figured by 



Owen in his i Odontography,' pi. lxxii. fig. 12, and his 

 'Cretaceous Reptilia' (Mon. Pal. Soc), pt. i. pi. ix a. 

 figs. 3, 4, and also by Charlesworth in the ' London Geolo- 

 gical Journal,' no. i. pis. iv., v., when it was less imperfect. 

 This specimen is the type of M. stenodon. 



Toulmin-Smith Collection. Purchased, 18G9. 



41640. One imperfect half of the siliceous cast of the pulp-cavity 

 (Fig.) of a tooth, probably belonging to the same individual as 



1 'Odontography,' p. 261 (1840). 



2 Oharlesworth's 'London Geological Journal,' no. i. p. 23^(1846). 



3 Jahrb. k. preuss. geol. Landesanst. for 1884, p. 32d (18sh). 



