1903.] -^'H', North American Cretaceous Fishes. 65 



with presented (Fig. 46). The anterior end of the fragment 

 is directed toward the right. The teeth are pleurodont, as 

 they are in Pachyrhizodus. They 

 have been crowded, as in Pachy- 

 rhizodus cauinus, but none of the 

 crowns has been preserved. The 

 roots present at least one differ- 

 ence from the species of Pachy- 

 rhizodus, so far as I have been able yXr. 46. Oyicardinus shearer i Cope. 



to observe. In the latter, when I^cVn'.'^- "" '' '^^''^^ ^^^''"' ""^ 

 the tooth separates from the root, 



which is buried in the bone of the jaw and becomes anchylosed 

 with it, the ring-like edge of the root is very sharp. In 0. 

 sheareri the remains of the root form a nearly flat ring around 

 the pulp cavity. This, looked at with a lens of high power, 

 shows radiating and concentric lines of dense bone. Nearly 

 all the teeth of the specimen appear to have been shed at 

 the time of its death; very few seem to have been broken 

 off afterward. The Museum number of the type is 1998. 



Oricardinus tortus Cope. 



Oricardinits tortus Cope (E. D.), Proc. Amer. Philos. Soc. XVII, 1877, 

 p. 177. — Woodward (A. S.), Cat. Foss. Fishes, IV, 1901, p. 46. 

 — Hay (O. p.), Bibliog. and Cat. Foss. Vert. N. A. 1902, p. 388. 



The type of this species is in the American Museum of 

 Natural History and has the catalogue number 21 14. The 

 material consists of a part of the left mandible, including 

 the symphysis, and possibly about twenty vertebrae. Figures 

 of the mandible are here presented showing it from the lingual 

 side (Fig. 47) and from the dental border (Fig. 48). In his 

 description, Cope deals much with the internal and external 

 ribs of this mandible, but it is difficult even with the speci- 

 men in hand to understand his meaning. The jaw has evi- 

 dently suffered some distortion and this has resulted in 

 making some of the anterior teeth appear to lie on the outer 

 side of the jaw. The teeth are much like those of Pachyrhizo- 

 dus, but the symphysis is different and the jaw is narrower in 

 l^yanuary, igoj.^ 5 



