FOSSIL FISHES. 43 
IscHyPTERUS BRAUN, 0. sp. 
Pl. XII, Fig. 3; Pl. XIII, Figs. 1, 2, 2a. 
Fishes three to five inches in length by one to one and a half inches 
broad; outline long-elliptical; body compressed; head relatively large, 
contained three to three and a half times in total length; teeth large, 
pointed, acute; cranial bones granulated; operculum semicircular, large ; 
preoperculum long-elliptical, having much the form of the operculum, but 
very much smaller; fins small, with delicate fulera and rays; dorsal and 
anal placed far back, dorsal midway between occiput and extremity of tail, 
very long from front to rear, fulcra small, rays ten; anal reaching back to 
or beyond base of caudal, fulera eight (?), rays five; jointed rays of caudal 
fin fifteen; scales rhomboidal or square, more uniform in size than any 
other species known, number along lateral line thirty-three, in vertical rows 
sixteen; scales of dorsal line rounded before, pointed or short-spined 
behind. 
This species is of peculiar interest as coming from the base of the 
Triassic rocks of New Jersey, from a horizon probably several thousand 
feet lower than that of the Boontor specimens, which are from near the top 
of the series. It may be distinguished from all other known species by the 
uniformity in the size of the scales and by the posterior position of the 
dorsal fin. The armature of the dorsal line is also less strong and con- 
spicuous than in most of the species of the genus; in this respect it is inter- 
mediate between the strongly spined species of Ischypterus, such as I. tenuiceps 
and those which have been grouped in the genus Acentrophorus by Dr. 
Traquair, of which we have an example in A. chicopensis, described in this 
memoir. In that fish all of the median scales of the dorsal line anterior to 
the dorsai fin are unarmed. 
The only locality from which fishes of the present species have been 
obtained is Weehawken, N. J. Here, beneath the trap of the Palisades, is 
a stratum cf highly metamorphosed slate which was once a bituminous 
shale, but which has been baked by the effusion of the great mass of molten 
matter above it; the fishes are found in this slate. In some layers it also 
