﻿268 SIRENOIDEI. 



palatine, laterally compressed ; ridges often prominent, sometimes 

 extending almost to the inner angulation. 



The possibility of this dental plate being the immature form of 

 C. latissimus is discussed by Miall, op. cit. 



Form. 6f Loc. Ilhaetic : Gloucestershire \ 



All the following dental plates were obtained from Aust Cliff, near 

 Bristol. 



(i.) Upper dental plates. 



P. 3392. Type specimen of C. obtusus, Agassiz, apparently owing the 

 obtuseness of the denticles to wearing during life. 



Enniskillen Coll. 



11211. Specimen figured by Miall, op. cit. pi. v. fig. 6. 



Mantell Coll. 



P. 4438 d. Plaster cast of dental plate figured by Miall, op. cit. pi. v. 

 fig. 4. Enniskillen Coll. 



P. 4438 e. Plaster casts of four dental plates. Enniskillen Coll. 



(ii.) Loiver dental plates. 



44834. Specimen with five denticles attached to bone and assigned 

 to the mandible by Miall, op. cit. pi. v. fig. 3. 



Presented by Benjamin Bright, Esq., 1873. 



28858 a. Specimen figured by Miall, op. cit. pi. v. fig. 7. 



Purchased, 1854. 



P. 4438 f. Plaster cast of fragment figured by Miall, op. cit. pi. v. 

 fig. 8; original in the Higgins Collection, Bristol Museum. 



Enniskillen Coll. 



As remarked by Miall {op. cit. p. 31), the so-called C. disauris, 

 Agassiz (torn. cit. p. 135, pi. xix. fig. 19, " C. bicornis "), is obviously 

 an abnormal dental plate. The type specimen (P. 493, Egerton 

 Coll.) was obtained from the Khaetic Section of Aust Cliff, near 

 Bristol, and is probably referable to C. parvus. 



Ceratodus guentheri, Marsh. 



1878. Ceratodus giintheri, 0. C. Marsh. Amer. Journ. Sci. [3] vol. xv. 

 p. 76, woodc. 



Type. Upper dental plate ; Yale College Museum. 



1 Dental plates from the Upper Keuper of Tubingen, Wiirtemberg, are also 

 considered to pertain to this species by F. A. Quenstedt, Handb. Petrefakt. ed. '3, 

 p. 298, pi. xxiv. figs. 4-8. 



