From Eocene to Recent Time 235 



ant, and have left remains from Wyoming eastward to 

 France and Germany; but they are represented only by a 

 few species in North America. 



The teleostean fishes belonged to families that evolved 

 from more primitive "ganoid" freshwater groups like the 

 Semionotidae, the Pholidophoridae, and the Leptolepidae, 

 and which have all remained in a freshwater habitat till 

 now. Thus the Cyprinidae, the Siluridae, the Chromidae 

 and the Aphredoderidae are examples. Others like the 

 Clupeidae, Percidae, Atherinidae, and Serranidae are still 

 in part freshwater, but have largely migrated into the sea, 

 while still others of early Eocene origin branched off rapidly 

 and wholly into marine surroundings as did the Carangidae, 

 the Scombridae, and the Sparidae, that are treated of from 

 the standpoint of descent in a later chapter. 



In addition to the above and other teleostean groups 

 like the Elopidae, the Albulidae, and the Chirocentridae, 

 that had already passed into the sea during Cretaceous 

 times, the sharks, dogfishes, and rays, as well as a few cest- 

 racionts must have been extremely abundant in individuals, 

 though dying out in species, when compared with Cretaceous 

 days. 



Here we might again emphasize the evident relation 

 of fishes to bituminous production. Thus Leidy in speak- 

 ing of the Green River Shales, from which Cope described 

 several freshwater fishes, remarks that at "Petrified Fish 

 Cut" are thousands of beautiful fish remains, sometimes 

 a dozen or more appearing over a square foot. of rock. 

 Remains of insects and aquatic plants are also found in 

 these shales, and in one instance a feather of a bird. In 

 darker brown bands that are intercalated amongst others 

 of a greyish-buff color, the former "are saturated with a 

 bituminous matter which renders them combustible." The 

 source here then evidently was from death and decay of 

 enormous shoals of freshwater fishes. Similarly A. S. 

 Woodward and von Ihering have described a series of 

 Tertiary bituminous schists at Taubate in the province 

 of S. Paulo, Brazil (77^:63). These contain a great 

 wealth of fossilized freshwater teleostean fishes, belonging 

 to the Siluridae, Characinidae, Serranidae, and Chromidae, 



