34 PALEONTOLOGY OF OHIO. 



Chemung rocks, where they should be carefully searched for. This pre- 

 diction has been verihed, as far as regards Dipterus, by the recent discov- 

 ery, by Mr. Andrew Sherwood, of a species of this genus iti the Oatskill of 

 Pennsylvania. 



The finding of Cocoosteus in the Comiferous limestone of Ohio is a 

 fact which will be regarded as discordant with the view that this was a 

 fresh water, or shore-inhabiting iish ; jsut the discordance is more appar- 

 ent than real, for the specimen now figured is unique in all the great 

 collections of fish remains made from the Corniferous limestone during 

 the last twenty -five years. 



This indicates the rarity of this fish in the sea of the Devonian age, and 

 the presence of its bones, in this one instance, in the sediment of that sea, 

 must be looked upon as an exceptional fact, like the finding of the floated 

 trunks of tree ferns in the same formation and locality. The open sea 

 was evidently not the kome of Coocosteus, either in America or in Europe. 

 The discovery of its remains here proves that it had a home in the West-, 

 ern Hemisphere, but we have not yet found it ; and the probability is 

 strengthened, that if sought in the shore and off-shore deposits of the 

 Chemung, Catskill, and Vespertine of Pennsylvania and ISTew York, the 

 remains of Coecosteus will be met with in greater abundance than any- 

 where in the Corniferous limestone. We may also look there for the 

 associates of Goocosteii,s in the old world — Pteriohthys, Cephalas'pis, 

 AccmtJiodes, etc., — -as the unity of the Devonian fauna is such that we 

 may expect to find in America representatives of all the more common 

 genera of the European Devonian rocks. 



In his interesting paper on Gerafodus J^orsteri, Dr. Gunther proposes 

 to group the Ganoids and Elasmobranehs together in one sub-class, to which 

 he gives the name of Palmiohthyes ; thereby indicating their antiquity. 

 He also makes the generalization that the Elasmobranehs were the 

 marine, and the Ganoids the fresh-water fishes of ancient times. With 

 this latter view, I cannot coincide, as I have elsewhere shown that in the 

 Devonian age the Ganoids far surpassed the Elasmobranehs in number 

 and size, and that they were the rulers of the seas as well as of the rivers 

 and lakes. This is proved by the abundance of the remains of the great 

 Ganoids, Onychodus, MacropetaUchthys, etc., in the Corniferous lime- 

 stone, which is unquestionably a marine formation ; and by the few and 

 smair relics of Elasmobranehs associated with them. Among the many 

 thousands of fish remains from the Corniferous limestone, which I have 

 examined, I have seen very few that could be referred to the group of Elas- 

 mobranehs. In the Carboniferous sea a different state of things prevailed. 

 ' There the Elasmobranehs were numerous and powerful ; while in this age 

 the Ganoids were almost exclusively confined to the shores and inland waters. 



