COPE ON GEOLOGY AND VERTEBRATE FOSSILS. 585 



The craniuin is flat above and without superior crests. The parietals 

 are small and in contact on the median line; the epiotics are small, and 

 the pterotics are large. The postfrontals are of moderate size, and the 

 frontals form the greater part of the cranial roof, and are completely 

 ossified. There is a large superciliary bone on each side, which connects 

 the pre- and post-frontals. If any part of the ethmoid is exposed, it 

 must be small. The premaxillary is coossified and transverse. The 

 maxillary bone is vertically compressed, and becomes, with its superior 

 supernumerary bone, widened in the distal portion. Proximally, it is 

 narrowed, and overlaps extensively the superior surface of the premax- 

 illary. There is an elongate preorbital bone extending downward and 

 backward, and there are several large postorbital bones which extend 

 nearly to the free border of the preoperculum. The latter, like the 

 other opercular bones, terminates in a thin, entire edge. iSix bran- 

 chiostegal rays have left their impressions, the inferior one with the 

 lower edge broken away. 



The inner face of the maxillary bone, the inferior faces of the premax- 

 illary and vomer, and the inner -superior aspect of the dentaries are 

 covered with acute bristle like teeth en brosse. The vomerine patch is 

 wide and transverse. 



To the remarks already made as to the affinities of this genus, it may 

 now be added that the dentition, with the superior position of the pec- 

 toral fin, resembles the characters of the MugilidcG. This genus must 

 doubtless be placed near SyllcGmus, as combining characters of the Phy- 

 sostomous and Physoclystous divisions. It differs from that genus in 

 the elevated position of the pectoral fins and the long dorsal fin. In 

 the latter point, it is similar to Apsopelix, but that genus has the deeply- 

 pitted vertebrre. Pelycorapis differs in its ctenoid scales and inferior 

 pectoral fin. 



Anogmius aratus Cope. 



The type-specimen on which this species rests was, when living, a 

 fish of about fifty pounds in weight. It is preserved in a mass of 

 chalk of the Niobrara formation, which is straw-colored internally and 

 lead-colored externally. This relation of these colors, which form two 

 horizons of the formation, shows, with other facts of the same kind, 

 that there is no important geological distinction between them. 



The head is wide and flat above in front. Behind the line of the 

 orbits, the superior surface displays three planes, the median narrowing 

 and rising posteriorly, terminating in a roof-shaped posterior border. 

 The muzzle is short and truncate ; the premaxillary transverse and hori- 

 zontal, and in the same slightly sloping plane as the front. The max- 

 illary is abruptly decurved, and the dentaries rise to meet the premax- 

 illary. The postorbital bones are much enlarged, as in Amia; the su- 

 perior cuts into the border of the pterotic; they number five, of which 

 the superior is above the line of the prominent superciliary border. 

 The operculum is extended backward and upward, and the suboperculum 



