82 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Marginal fringe of minute teeth present on the external alveolar border 

 of the dentary: 



Dolichus group. 



Smaller than E. petrosus and E. dims; palatine relatively slender; 

 palatine fang laterally compressed, and grooved but not fluted as in 

 E. amicrodus; length of the fang varies with the size of the speci- 

 men, from 7 to 23 mm Enchodus dolichus 



Very small, with bones as thin as paper; length of palatine fang, from 2 

 to 10 mm Enchodus shumardi 



Enchodus petrosus Cope. 

 This species was first described by Dr. E. D. Cope in 1874. 

 The description was based upon very fragmentary material. 

 The deplorable custom of hastening to describe a new species 

 upon the discovery of a few bits of bone has resulted in a vague 

 definition of this as well as of other species of Eyichodus. The 

 best specimens of this species are shown in plates II, III, IV, 

 V, VI, VIII, and IX. It is a large species, but not so large as 

 the unnamed species represented by figures 3, 4 and 5 of plate 

 II. The specimen represented on plate VIII, and in part on 

 plate IX, together with other material, was kindly loaned to 

 the author by the American Museum. The tj'pe specimen of 

 E. petrosus was included with these specimens. Although Dr. 

 0. P. Hay has described this specimen (pi. VIII) as a new 

 species, E. ssevus, a careful comparison of all of the specimens 

 has convinced the writer that it is identical with E. petrosus. 

 The type of Enchodus petrosus, a palatine, has no fang pres- 

 ent ; but there seems to be no good reason for supposing that 

 this type specimen had a fang compressed differently from the 

 fangs of the numerous palatines, which it so closely resembles, 

 represented in the collection. Since such extensive variation is 

 to be observed in all of the specimens, a more or less distinct 

 cutting edge on a palatine fang, it seems, would not indicate a 

 new species, but only a variant. Nor should the manner of 

 compression in the palatine fang serve alone as a criterion, 

 since considerable variation is apparent here also. Fish bones 

 are not very resistant, and the fangs as well as other portions 

 are found to be twisted, due to uneven pressure of the matrix. 

 The fang shown in plate II, figure 1, pal, has undergone torsion, 

 so that the distal end is now compressed almost laterally. The 

 specimen described by Dr. 0. P. Hay as E. ssevus (Hay, 1903) 

 is refigured in plates VIII and IX. Doctor Hay has figured 

 a palatine, preopercular, and what seems to be a premaxillary. 

 Regarding the palatine and the premaxillary there is evidently 



