COPE ON ICHTHYIC FAUNA OF THE GREEN RIVER SHALES. 819 



Number of si^ecies 



Dapedoglossus 

 Diplomystus . . 

 Erismatopterus 

 Ampliiplaga . . . 



Asineops 



Mioplosns 



Priscacaia 



The Herriug {JDiplomystus) exceed all others in number of species and 

 individuals. One of the species (Z>. liumilis) is more abundant than all 

 the other species of all genera put together. Long after these come, in 

 point of numbers, the more typical spinous-rayed species, which doubt- 

 less preyed upon them. The following species are represented by but one 

 individual each: — Diplomystus dentatiis, Erismatopterus endlichii, Am- 

 pliiplaga hrachy2)t€ra, Asineons pauciradiatus, Mioplosus abhreviatiis, M. 

 beanii, and Priscacara cypJia. 



A consideration of the fauna with the additional light derived from 

 this accession of new material is of some value in connection with the 

 question of the relation of this formation to the oceans and lakes of the 

 Eocene period. I have heretofore expressed the opinion that the Green 

 Eiver water-area in which the shales were deposited may have had, 

 like the Wasatch Lake of Xew Mexico, connection with the sea, and 

 pointed out the broad distinction between its fish-fauna and that of the 

 undoubtedly land-locked lakes of the South Park of Colorado and of 

 Elko, Nev. The fishes of the latter formation are nearly related to 

 fresh-water types only, and to those at present inhabiting North Amer- 

 ica. On the other hand, the Green River Shales contain two striking 

 representatives of families which do not now exist in North America, 

 and very rarely in any of the northern realms of the earth. These are the 

 Osteoglossidw, whose genera are all fresh- water, and the Fharyngo- 

 gnathi, with ctenoid scales. Some of these are marine {Fomacentrid(c), 

 and others are fresh-water {Cliromididcv). The Green Eiver genus P;-«6^- 

 cacara is, in some respects, more nearly allied to the latter than the for- 

 mer family, but not entirely so. 



The remaining genera (excepting Asineops) correspond to existing 

 North American genera, viz : — Diplomystus^ to Glupea ; JErismatopterus 

 and Amphiplaga, to Aphredodirus ; and Mioplosus, to Lahrax. The first- 

 and last-named recent genera are anadromons, and Aphredodirus exists 

 in tide-water ; it has also been found near the Cheat Lakes. We look 

 for further material to throw light on the question of possible marine 

 communication with the Green River lake. 



