228 

 EMPO, Cope. 



This genus is represented by very numerous remains in the chalk of 

 Kansas, and a considerable amount of material pertaining to it has come under 

 my observation. The best-preserved remains are vertebrae and the jaws ; all 

 other portions of the skeleton are so fragile as to be difficult of extraction 

 from the matrix, but a few specimens preserved by the care of Professor Muclge, 

 of Kansas, have thrown especial light on these little-known parts of the 

 structure. 



The premaxillary bones are longer than in any other genus here described, 

 and terminate anteriorly in a compressed-conic apex of dense bone. Medially, 

 they have greater transverse thickness and a semicircular section; while, dis- 

 tally, they are compressed, and extended vertically. There is an unsymmctiical 

 crest on the superior border, the only point of contact with the ethmoid. The 

 maxillary is continuous from this point, and is usually attached by the coossi- 

 fication of a squamosal suture. It is vertical and flat, and probably of no 

 great extent. The extremity is broken off in the specimens. While the pre- 

 maxillary supports two series of teeth, the maxillary presents but one. 



The dentaries support several series of. teeth ; one of large ones on the 

 inner side, and several smaller on the outer. The small ones are double- 

 edged, and diminish in size to the external margin ; the inner ones are like 

 the large ones of the maxillary series, with a flattened cutting apex. A strik- 

 ing character observed in two species of the genus (E. nepceolica and E. senii- 

 anceps) is the absence of any angular process' of the mandible ; the narrow 

 angular bone being truncate vertically from the transverse cotylus. 



There are other tooth-bearing bones, which I cannot positively locate. 

 Some of these are laminiform, and are covered on one edge, and for some dis- 

 tance on the adjacent sides, with a dense brush of small acute conic teeth. 

 Tnis bone is palatine or pterygoid. Another is a massive tongue-shaped bone 

 with one narrowed extremity, and the other expanded into a lamina in the same 

 plane. It supports a median series of teeth, mostly in two rows, whose 

 crowns are curved and simply conic. This bone is sometimes nearly symmet- 

 rical, so as to resemble a vomer; but in others it is distinctly unsyinmetrical. 

 It is probably a superior or inferior pharyngeal. In one specimen, it lies 

 pressed down on the dentary, with the teeth on the inferior side. Another 

 bone is rod-like, with triangular section, with a single row of small conic 

 teeth set on the edge, whose section yives an angle. 



