706 E. C. CASE 



direction, and the other two in the other. Between the last of the latter and 

 the inner border is a rudiment of another in the form of a rugosity. None 

 of the crests touch each other at their bases. At their extremities they 

 curve rather abruptly downward, and do not project beyond the inferior plane, 

 from which each one is separated by a deep fossa, whose mouth is a notch 

 in its base. The crests are coarsely dentate, there being three or four teeth 

 on each, and the grooves between them are marked by coarse transverse 

 undulating grooves. The inner border is a deep vertical plane ; the inferior 

 face is narrow and concave in transverse section." 



MEASUREMENTS. 



"Total length ------- .o22 m 



Greatest width ------ .007 



Depth at middle __;_•_,_. .006 " 



" It differs from the C. serratns of Newberry in its narrow form, small 

 number of ridges and the very slight prolongation of their extremities." 

 I No. 6506.] 



Sagenodus heterolophus Cope. 



Ctenodus heterolophus Cope, 1883, Proc. Acad. Nat. Sc, Phil., 



p. 109. 

 Sagenodus heterolophus Woodward, 1891, Cat. Foss. Fishes 



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

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



Series A, p. 176. 



" This species is represented by a single broken tooth, which presents 

 remarkable characters. It had apparently, when perfect, but three crests, which 

 differ greatly in length, diminishing very rapidly from the first or marginal crest, 



" The crest just mentioned is not only longer, but much more elevated 

 than the others, except at the base, where the second crest is the highest. 

 But while the first rapidly rises, the second retains its elevation, and then 

 descends, forming a convex edge, of which the distal part is obtusely serrate. 

 The proximal part of the first crest is worn by friction with the opposing edge 

 of the opposite jaw into a sharp edge, below which its base is covered by a 

 thin layer of the shining cementum which invests the teeth and sides of the 

 second crest. The amount of this shinning layer is thus more extensive than 

 in any other species of Ctenodus known to me. The third crest, judging by 

 its base of continuity with the second, is very small." 



MEASUREMENTS. 



" Elevation of first crest at middle - - .0095"' 

 Elevation of second crest at middle - - .0065 

 Length of a tooth of second crest - .0020 



[This specimen is missing from the collection.] 



