164 AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



This species was founded on an immature, imperfect dental plate. 

 Subsequently well-preserved, mature plates were obtained by Cope from 

 the same locality and described as distinct species under the names given 

 in the synonymy above. It appears very plainly, however, after a com- 

 parison of ten dental plates in the American Museum and in the University 

 of Chicago collections, representing these forms, that they are only varia- 

 tions of one species. For this the name Sagenodus fossatus should be used 

 because of priority. 



Revised description: Dental plate with six or seven ridges radiating from 

 an inner smooth area; these ridges separated from one another by very_ deep 

 grooves. Each ridge with several (three to six) coarse denticulations in its 

 distal half, but proximal half sharp and even, gradually descending towards 

 the inner smooth area. 



Sagenodus (Ctenodus) heterolophus Cope (Proc. Acad. Nat. Sci. Phila., 

 1883, p. 109) was founded on "a single broken tooth" which was de- 

 scribed but not figured. The description is quite inadequate, leaving open 

 the question whether the specimen was not an imperfect S. fossatus. The 

 whereabouts of the type are unknown. A specimen in the American Mus- 

 eum, No. 7473 (plate 27, fig. 6), is perhaps this type, as it answers in a mea- 

 sure to the dimensions given by Cope; but of this there is no certainty. It 

 presents the three anterior ridges of a lower dental plate, of which the most 

 anterior ridge is higher than the succeeding ones. On the whole, S. hetero- 

 lophus can not be regarded as a valid species since it was not sufficiently 

 described. 



Sagenodus paucicristatus (Cope). (Plate 27, fig«. 4, 4a.) 



1877. Ceratodus paucicristatus Cope, Proc. Amer. Philos. Soc, xvn, p. 53. 



1877. Ptyonodus paucicristatus Cope, Ibid., p. 192. 



1891. Sagenodus paucicristatus Cope, Woodward, Cat. Fos. Fishes, Brit. Mus., 11, p. 261. 



1899. Sagenodus paucicristatus Cope, Williston, Kans. Univ. Quart., Ser. A, viii, p. 175. 



1900. Sagenodus paucicristatus Cope, Case, Journ. Geol., vni, p. 707. 



Type: An imperfect dental plate. No. 6505 University of Chicago 

 Gurley Collection. Vermilion County, Illinois. 



Original description: "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. m 



"Length from base to second rib 0.0170 



Depth at base of second rib 0045 " 



I may add that while only four ridges are preserved in the type, a com- 

 parison with other species indicates that at least two more must have been 

 present. The ridges are sharp and devoid of the denticulations so con- 

 spicuous in some other species, e.g., Sagenodus fossatus; the_ second ridge, 

 however, shows at its distal end two faint elongated crenulations. 



