340 0. C. Marsh— Vertebrate Life in America. 
Petalorhynchus; and of the  Slgeirma the genera eli, 
Carcharopsis and Diplodus. e Hlasmobranchs were the 
rulers of the Carboniferous open sea, and more than one hun- 
smaller size, an denizens of the more shallow and confined 
waters. The latter group of fishes was represented by true 
Lepidostide, of the genera Paleoniscus, Amblypterus, Putgac 
mus and Hurylepis. Other genera are, Rhizodus, Megalichthys, 
Ctenodus, Edestus, Orodus, Clenacanthus, yracanthu s, and Cela-. 
canthus. Most of these genera occur also in Europe. 
rom the Permian rocks of America, no vertebrate remains 
are known, although in the same formation of Europe Ganoids 
are abundant; and with them are remains of Sharks, oes sie 
other fishes, the affinities of which are doubtful. The 
zoic fishes at present known from this country are ive vi 
numerous as those found in Hurope. 
In the Mesozoic age, the Fishes of America begin to show a 
decided approach to those of our present waters. From the 
Triassic rocks, Ganoids only are known, and they are all more 
or less closely related to the modern Gar- -pike, or Lepidosteus. 
‘They are of small — ee the number of individuals 
preserved is very larg: e characteristic genera are, Catop- 
terus, Ischyplerus, Bichotepta, Rhabdolepis, and Turseodus. 
rom the Jurassic deposits, no remains of fishes are known, 
but in the Cretaceous, ichthyic life assumed many and 
various forms; and the first representatives of the Teleosts, 
or bony fis es, the characteristic fishes of to-day, make 
their appearance. In the deep open sea of this age, Hlas 
mobranchs were the eae forms, Sharks and Chimeeroids 
being most numerou n the great inland Cretaceous sea of 
and many of them of large size. The Ganoids were compara- 
“aden few in number. In the earliest Eocene fresh-water 
deposits, it is interesting to find that the modern Gar-pike, 
