46 



cies, marked with raised radiating ribs, or inosculating ridges, whose 

 edges are sometimes serrate. 



Several species of this genus appear to have existed. I originally- 

 referred some of them to Dr. Leidy's genus Cimolichthys ; but I find 

 that they do not possess the same type of teeth. The Umpo nepaeolica 

 probably belongs to it, and the generic characters formerly given express 

 the peculiarities of dentition of the distal part of the maxillary bone. 

 The genus therefore takes this name. From several allied genera here 

 enumerated, it difi'ers in the presence of the outer series of small teeth 

 on the dentary bone, and the inner series of the maxillary, with the 

 absence of long teeth on the front of the former. 



Empo nepaeolica. Cope, Proceed. Amer. Philosophical Soc, 1872, 347. 

 Niobrara epoch of the Smoky Hill region. 



Empo sulcata. Cope ; CimoUcJithys sulcatus, Cope, loc. cit., 351. 

 jSTiobrara epoch of the Smoky Hill and of Books County, Kansas. 



Empo semianceps. Cope ; Cimolichthys seinianceps, Cope, loc. cit., 351. 



Niobrara epoch of the Smoky Hill region, and of Trego and Eooks 

 Counties, Kansas. 



Empo merrillii, sj). nov. 



Indicated by numerous portions of cranial feones, including those sup- 

 porting the teeth. On the proximal part of the maxillary, the large teeth 

 grade into those of the small inner series insensibly ; at the distal end 

 the two large ones of the inner side are opposite to the reduced ones of 

 the outer series. Both maxillary and mandibular teeth are striate- 

 grooved on the outer side at the base. The pharyngeal bone is 

 peculiar in not bring widelyiexpanded at one end, and in having a nar- 

 row basis generally for the two rows of teeth it supports. The (?) palatine 

 bone exhibits the teeth en brosse, seen in U. semianceps^ but principally 

 on one side, and the thickened edge supports on one of its marginal 

 angles a series of much larger conical teeth. 



Measurements. 



M. 



Width of maxillary inferiorly at middle 0. 012 



Depth of maxillary distally . 018 



Depth of maxillary proximally Oil 



Depth of (!) palatine 018 



Width of pharyngeal bone at middle 009 



Niobrara epoch of Ellis County, Kansas. Dedicated to Professor 

 Merrill, of Topeka, who has made a nuhiber of important additions to 

 our knowledge of the extinct vertebrata of Kansas. 



Empo contracta, sp. nov. 



Considerable portions of a cranium of a species of the lesser size of 

 the E. sem^ianceps resemble corresponding parts of that species, with 

 certain marked exceptions. These are seen in the flatness of the maxil- 

 lary bone, and the large size of the inner row of teeth. The inner face 

 of the maxillary is very narrow, by reason of the depression of form. 

 The proximal end of the same is, on the other hand, a little compressed.. 



