284 KANSAS UNIVERSITY SCIENCE BULLETIN. 



four. There may have been as many as forty-five or fifty in 

 the complete fish. They are fully ossified, slightly constricted 

 and marked with small longitudinal ridges. The length is 

 slightly greater than the depth. The neural spines are long 

 and interlock with the interneurals. Supernumerary ribs 

 present. Six of them occupy the space of a single vertebral 

 centrum. 



The specimen as preserved is well characterized by the fig- 

 ures. The fish lacks the posterior end of the body back of the 

 anus. It is chiefly remarkable on account of the extraordinary 

 preservation of the casts of the rectum and intestine, of which 

 there are six coils or loops preserved. The remains are em- 

 bedded on the right side in a calcareous, arenaceous, shaley 

 limestone, which also contains remains of some species of 

 Inocey^amus, small fish teeth and the base of a moderately 

 large shark's tooth. 



Perhaps the most interesting portion of the entire specimen 

 is the intestinal canal, from the presence of which is derived 

 the specific name. In general features the alimentary canal as 

 preserved recalls that of the common fresh-water buffalo fish, 

 Ictiobus bubalus Raf (plate LXII, figure 1). The similarity 

 in form is undoubtedly indicative of similarity of habit, and 

 since we know that the buffalo fishes are bottom feeders we 

 can easily predicate that our ancient Cretaceous fish had similar 

 habits and at the time of its death the alimentary canal was 

 filled with mud mixed with some organic substances ; for the 

 fossil shows a different texture for the cast of the alimentary 

 canal from the matrix, indicating different materials. The 

 intestine as preserved consists of six coils or loops of the very 

 small intestine which immediately precedes the rectum, which 

 is likewise preserved. The rectum is elongate but no more so 

 than is the same structure in the buffalo fish. The essential 

 characters are shown in the illustrations. 



The distinction of this species from the other three which 

 have been assigned to Thrissopater is to be found, first of all, 

 in the posterior location of the pelvic fin. Its base lies at a 

 distance posterior to the back edge of the dorsal fin, which is 

 equal to its own length. So far as I am aware the large axil- 

 lary scale in other species of Thrissopater is larger and un- 

 ornamented. From T. salmoneus Giinther the present form is 

 to be distinguished by the relative proportions of the head and 



