72 KANSAS UNIVERSITY SCIENCE BULLETIN. 



suggestions. He wishes to thank the American Museum also, 

 through Dr. Louis Hussakof, for the loan of their specimens 

 of Enchodus. Most of the specimens studied were prepared by 

 the author under the direction of the assistant curator of 

 paleontology, Mr. Handel T. Martin. 



All of the drawings were made by the author. Those for 

 figures 3, 4 and 5 of plate II, all of plates III, V, VI, X, XI, XII, 

 XIII and XV were made in the following manner : The speci- 

 mens were photographed and then carefully traced in India 

 ink, after which the silver salts were removed by means of a 

 thorough washing in a solution of potassium cyanide. This 

 process insures greater accuracy of detail and proportion.s 

 than is possible otherwise with the most painstaking measure- 

 ments. Drawings for plates VII, VIII and IX were made di- 

 rect from the specimens by means of measurements. Draw- 

 ings for plates XVI and XVII were made by means of the 

 camera lucida. 



The literature on Enchodus shows that there have been at 

 least sixty-nine different names proposed for the various 

 species of the genus. Thirty-eight of these have been found 

 to be synonymous. Thus about thirty stand as valid species. 

 Since many of these have been based upon fragmentary ma- 

 terial, it is quite probable that this number will be much re- 

 duced as more complete specimens are found. Except in the 

 posterior regions of the skull, the bones are so loosely articu- 

 lated that specimens with the elements in position are not 

 often collected. Such parts as the palatines, single teeth, or 

 the cephalic ends of the dentaries are frequently found associ- 

 ated with no other part of the skeleton. This condition, to- 

 gether with the wide distribution of the species and the ex- 

 treme variability of so many of the characters, as the size of 

 the teeth, their relative proportions, the striations and ridges 

 on the teeth, their number, the angle which the palatine fang 

 makes with the palatine, depth of the dentary, and some others, 

 which have been used in the determination of species, accounts 

 for the large synonymy to be found in Enchodus literature. 



Specimens have been collected in the United States from 

 Kansas, South Dakota, New Jersey, Delaware, and New Mex- 

 ico. In all about fifteen species have been described, mostly 

 based on fragmentary material. The genus has also been col- 

 lected in the Senonian and Turonian of England, Turonian of 



