268 
SIREXOIDEI. 
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 Log. IthaBtic : Gloucestershire h 
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.) Lower 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 (tom. 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 Bhtetic Section of Aust Cliff, near 
Bristol, and is probably referable to C. parvus. 
Ceratodus guentheri, Marsh. 
1878. Ceratodus giintheri, 0. C. Marsh. Amer. Jouru. Sci. [3] vol. xv. 
p. 76, woodc. 
Type. Upper dental plate ; Yale College Museum. 
• 1 Dental plates from the Upper Iveuper 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. 
