GEOLOGICAL SURVEY OF THE TERRITORIES. 425 



VII— ON THE FISHES OF THE TERTIARY SHALES 

 OF GREEN RIVER, WYOMING TERRITORY. 



By Professor Edward D. Cope. 



Pkysoclysti. 

 ASINEOPS, (Cope.) 



(Proc. Amer. Phil. Soc, 1870, p. 380.) 



Bran chiostegal radii, seven ; ventral radii, I. 6-7. Opercular and other 

 cranial bones unarmed; scales cycloid. Spinous and cartilaginous dor- 

 sal fins continuous; caudal rounded ; anal with two spines. Lateral 

 line distinct. Operculum with regularly convex posterior border. Teeth 

 coarsely villiform, without canines. Both spinous and soft portions of 

 dorsal and anal fins moderately scaly. 



This well-marked genus is established on the remains of fifteen indi- 

 viduals, in various states of preservation, so that the characters undis- 

 tinguishable in one, can be discovered in another. Thus the lateral line 

 is preserved in one only, and the teeth in another. In none can I be 

 entirely sure that I see the vomer. 



The scales are preserved in many specimens, and I cannot find a 

 ctenoid margin in any, nor any radiating sculpture, but delicate concen- 

 tric ridges continued around the central point proximally, distally form- 

 ing parabolic curves, the less median not completed but interrupted by 

 the margin of the scale. Near the margin all the ridges become gently 

 zigzagged. 



There is no depression between the two portions of the dorsal fin, 

 though the cartilaginous portion is the more elevated. Laid backward, 

 the latter is in line with the extremity of the anal, and both it and the 

 anal extend beyond the basis of the caudal. 



The affinities of this genus are rather obscure, but are in some degree 

 related to that aberrant family of Physoclysti, the Aphredodiridce. This 

 is indicated by the increased number of ventral radii, the slender sepa- 

 rated pubes, and the reduced number of interneural spines. The Aphre- 

 dodiridce betray a physostomous tendency in the same characters, with 

 still greater reduction of the spinous, dorsal, and anal fins, though its 

 ctenoid scales and spinous orbital and preopercular bones are of phy- 

 soclyst significance. In Asineops the scales are cycloid and the cranial 

 bones unarmed. The v*entral fins occupy nearly the same position as in 

 the extinct genus Prismatopterus, Cope, which accompanies it, and which 

 is nearly allied to, if not one of the Cyprinodontidw. There is at least 

 in these genera another illustration of the approximation of forms, now 

 very distinct, in past periods. The pubes are, however, supported by 

 the clavicles in Asineops, by the post-clavicles in Prismatopterus, though 

 the latter bones are very long in Asineops also. Asineops and will thus 

 constitute a family, Asineopidce "differing from the Aphredodindw in the 

 simple pubes. I suspect that the genus Pygceus of Agassiz will be 

 found also to belong to it, though no such increased number of ventral 

 radii is assigned to it in the Poissons Fossiles. Some of its species may 

 even be found to belong to Asineops. Nine are described by Professor 

 Agassiz, all from Monte Bolca, in Italy, from an upper eocene stratum. 

 The presence of so near anally as Asineops in the Green Biver beds 

 suggests an approximate identity of age. 



