28 TRIASSIC FISHES AND PLANTS. 
all the fins are quite strong, and the scales are large, broad, and thick. The 
concentric lines upon their borders, mentioned by Mr. J. H. Redfield, are 
not peculiar to this species, but are more or less distinctly visible in all the 
members of the genus in certain states of preservation. It is most notice- 
able where the scales are partially decomposed and where they were of 
considerable thickness. In outline the fishes of this species resemble some 
individuals of Ischypterus tenuiceps, but they are considerably larger, the 
scales are also relatively larger and more quadrate; the arch of the back 
is usually regular, and the outline is comparatively smooth, never showing 
the extreme development of the dorsal scales which is so conspicuous a feat- 
ure in the older individuals of I. tenuiceps. 
Judging from some of the specimens obtained from Turner's Falls, I 
am inclined to think that this is the fish which is figured by Sir Charles 
Lyell in his paper on the Virginian coal field and referred to by Sir Philip 
Egerton as a species of Tetragonolepis. In that specimen nothing is shown 
but a portion of the side near the head, without tail or fins. If the fins 
had been present they would probably have shown the great development 
of the fulera, which is characteristic of Ischypterus and wanting in Tetrago- 
volepis. This I infer from the facts that no other traces of the latter genus 
have been found in the Triassic rocks of North America, and the scales on 
the sides of the large and broad species of Ischypterus could hardly be dis- 
tinguished from those of a corresponding part of the body in Tetragonolepis. 
With precisely similar scales, however, we have in several instances the . 
characteristic fins of Ischypterus. No such specimens were contained in 
the collections made by Sir Charles Lyell in America, and the inference of 
Sir Philip Egerton was therefore a natural one, though probably erroneous. 
Iscuyprerus Marsnir W. ©. BR. 
Pl. Il, Fig. 1. 
Fishes twelve inches or more in length by three or four inches in breadth; 
body fusiform in outline; head conical, obtuse, contained four and one-half 
times in the entire length; fins strong but relatively short; anterior base of 
dorsal midway between muzzle and tip of tail; fulera strong and short; rays 
