PERMIAN VERTEBRATES 707 



Sagenodus paucicristatus Cope. Plate I, Figs. 11a, lib. 



Ceratodus paucicristatus Cope, 1877, Proc. Am. Phil. Soc, 



P- 54- 

 Ptyonodus paucicristatus Cope, 1877, Proc. Am. Phil. Soc., 



p. 192. (Pal. Bull., No. 26.) 

 Sagenodus paucicristatus Woodward, 1891, Cat. Foss. Fishes 



Brit. Mus., Pt. II, p. 261. 

 Sagenodus paucicristatus Williston, 1899, Kans. Univ. Quart., 



Series A, p. 175. 



"The single tooth representing this species is narrow in the transverse 

 direction, but stout in vertical diameter. But four ridges are present, all of 

 which have a single direction, but the shorter ones are the less oblique to the 

 long axis of the tooth. They all extend into the inner border but become low 

 as they approach it. Distally they are quite prominent, but do not project very 

 far beyond the emarginate border between them. The inner border is plane 

 and vertical, and without ledge; the inferior surface is concave in the transverse 

 direction. The surface of the tooth is minutely and elegantly corrugated." 



MEASUREMENTS. 



" Length from the base of second rib - - - .017 m 

 Depth at base of second rib - - - - - .0045 " 



[No. 6505.] 



Peplorhina arctata Cope. 



Peplorhina arctata Cope, 1877, P roc - Am. Phil. Soc, p. 55. 

 Theromorphous Saurian, Proc. Am. Phil. Soc, 1882, footnote 

 to p. 461. (Pal. Bull., No. 35). 



The species was based on an imperfect bone bearing small teeth. From 

 its resemblance to the palatal teeth of Peplorhina anthracina the author 

 refers it to that genus with the remark that " this course is open to modifica- 

 tion should subsequent investigation require it." Later, in 1882, he remarks 

 in a footnote ; " Peplorhina arctata Cope from the Illinois Permian is not a 

 Peplorhina but a Theromorphous Saurian'' 



The broken specimen originally described certainly has much the appear- 

 ance of the small teeth which occur in the roof of the mouth of certain of the 

 Cotylosauria and may very possibly belong there, but there is present in the 

 collection a complete plate showing no sutural edges. It is certainly a plate 

 from the mouth of a Crossopterygian fish, and as the description of the perfect 

 portions of Cope's specimen applies very perfectly to it, it may best be con- 

 sidered under the original name. The applicable portion of the original 

 description is as follows : " The convex surface (of the plate) is thickly 



