372 University Geological Survey of Kansas, 



LEPTICHTHYS. 



Stewart, Am. Geol., vol. XXIV, pp. 78, 79. 



There are several specimens of Cretaceous fishes in our col- 

 lection that seem to differ from any of the other genera that I 

 have seen described, and for which I have ventured to propose 

 the generic name of Leptichthys. This genus seems to be related 

 to Osmeroides Agassiz in some respects, but differs from it in the 

 presence of a short dorsal fin and non-striated scales. It also 

 differs from Apsopelix Cope in the anterior position of the dorsal 

 fin. 



The body is ellipsiform, and covered with large, thin cycloid 

 scales, which are concentrically striated ventrally, but seem to 

 lose this character to some extent in the dorsal region, where 

 they are somewhat rugosely marked. The pelvic bones seem 

 to be formed of heavy transverse bars of bone, which are thick- 

 ened externally for the attachment of the pelvic fin. These 

 bones probably had some anterior extension, but how much 

 cannot be ascertained from the specimens at hand. The dorsal 

 fin is short and composed of numerous rays, which are situated 

 in front of the middle portion of the body. The pectorals are 

 broad and rather elongated. The pelvic fin is broad and short. 

 The caudal fin is deeply cleft. The skull seems to be rather 

 bluntly pointed in front. The dentaries are short with acutely 

 pointed teeth, and the lower borders of the bones are directed 

 upward in front. The vertebrae are two-grooved, and are longer 

 than deep. Only one species is represented in our collection, 

 which is described below. 



Leptichthys agilis, sp. nov. Plate LXXII, fig. 1. 



Scales large ; about ten or twelve series to be seen across the 

 body. The pectoral fins are composed of at least fourteen rays, 

 the first two or three of which are cross-segmented, while the 

 remainder are longitudinally split. The pelvic fins are situated 

 posteriorly and the cross-segmentation is absent from their rays. 

 The dorsal fin is composed of twelve or more short bony rays. 



