228 0. P. Hay — Notes on species of lchthyodectes. 



slope was probably continued forward by the premaxillary. 

 In a fragment of the dentary which I regard as belonging to 

 this species there is preserved one tooth complete. It is 

 straight, 7""" high and the enamel is smooth. 



lchthyodectes arcuatus Cope and I. poly micro das Crook. 



Portheus arcuatus Cope, 1875, Cret. Vert., pp. 193, 204, 274, pi. xlvii. flgs. 7-!i 



(figures doubtful). 

 Iditlnjodectcs arcuatus Cope, Proc. Amer. Philos. Soc., vol. xvii, p. 177; 1892, 



Amer. Nat., vol. xxvi, p. 942. 

 lchthyodectes polymicrodus Crook, A. J., 1892, Paheontograpliic-a, vol. xxxix, p. 112, 



pi. xvi. 



In Palceontographica, as above cited, Dr. Crook has described 

 as new a species of fossil fish from the Cretaceous deposits of 

 western Kansas and has bestowed on it the name lchthyodectes 

 polymicrodus. This species he compares with Prof. Cope's 

 lchthyodectes multidentatus and concludes that the two are 

 distinct species. In this conclusion he is doubtless correct, 

 because of the evident difference in the size and number of 

 teeth in the two forms. I can, however, with difficulty accept 

 Dr. Crook's statement that the maxilla of his species possessed 

 24 teeth to the centimeter. This might possibly be true of the 

 distal end of the maxilla, where they become very small, but 

 not for the anterior end, even according to Dr. Crook's figure. 

 In Cope's species, /. midtidentattts, there were only 5 teeth to 

 the centimeter. 



In a review of Dr. Crook's paper (Amer. Naturalist, vol. 

 xxvi, p. 941) Prof. Cope claims that Dr. Crook's species is the 

 same as that originally described by Cope as Portheus arcuatus, 

 and which is retained by Crook in Portheus, but transferred 

 by Cope to lchthyodectes. It is hard to understand why the 

 species was originally placed in Portheus, since its dentition is 

 very different from that of this genus. There appears to have 

 been some confusion in Prof. Cope's mind regarding this 

 species. It was founded on somewhat imperfect maxillary and 

 palatine bones, and the original description given of it pertained 

 to these bones. (Cret. Vert., p. 204.) On page 274 of the Cre- 

 taceous Vertebrates, under this species, Cope refers to plate 

 xlvii, figs. 7-9. When we turn to this plate we find figures 

 of what appears to be an lchthyodectes. On the plate they are 

 said to belong to ? Portheus arcuatus ; while in the explana- 

 tion of the plate they are referred to Portheus f arcuatus, 

 We are therefore unable to say whether Prof. Cope was in 

 doubt as to the species or the genus. On page 220 B, line 16, 

 two of the same figures are mentioned as those of " the 

 cranium of an unknown species" of Saurodontidae. In his 

 review of Dr. Crook's paper, Prof. Cope states that had it not 

 been for certain conditions the figures of his species would have 



