FOSSIL FISHES. 39 
Collected at Boonton, N. J. Types in geological museum of Colum- 
bia College. 
IscHYPTERUS LENTICULARIS, D. sp. 
Pl. X, Figs. 2, 3. 
Fishes six to six and a half inches long by two to two and a half 
inches wide; general outline lenticular; body widest at the middle, sloping 
gently to the muzzle and tail; head pointed or obtuse, relatively large, a 
little less than one-quarter of the entire length; fins all small and delicate 
for the size of the fish; scales apparently thin, those of the dorsal line 
relatively small. 
Among several hundred fishes obtained at Boonton, N. J., there are a 
number which correspond to the above description. They are relatively 
broad and have a nearly symmetrical lenticular outline, the tail being small 
and the body at its base only about one-third as wide as before the dorsal 
fin. The fins are all small and weak, the fulera slender, nearly straight 
and closely appressed. The general form is similar to that of I. ovatus, 
but these fishes are not half the size of those to which W. C. Redfield 
gave that name, and the whole structure is much more delicate. In J, 
ovatus the scales of the dorsal line and sides would seem to have been very 
thick and strong, the fins are large, the fulera strongly arched. The rela- 
tion of these smaller oyoid fishes is rather with those to which I have given 
the name J. elegans, and here the differences may be those of age or sex. 
The group designated by the latter name consists of fishes which are much 
smaller, often not much more than half the length and breadth, the lower 
line of the body being nearly straight, the upper highly arched betore the 
dorsal fin, concavely narrowed behind. Hence I have supposed that they 
constitute a distinct species. | 
Up to the present time I have seen no such fishes as those under con- 
sideration at any other locality than at Boonton. There are none such in 
all the collections made at Durham or Sunderland. In the first of these 
localities I. micropterus apparently takes their place, but this, though like in 
the small size of the fins, is distinguished by its depressed, pointed muzzle 
and the cuneate outline of the body, which is widest immediately behind 
