TFOSSIL FISHES. 49 
the details of structure retained, and all the small fishes of the genera 
Catopterus and Ischypterus which I have thought worthy to be figured have 
been obtained: there. 
It is somewhat remarkable that among the thousands of presumably 
mature individuals of all the six genera yet found in our Triassic rocks 
the young are so generally absent. Some difference in size is perceptible 
among those which we suppose to represent the twenty-eight known species, 
but if young and old were in the habit of associating together we ought to 
have graded sizes of many of the species. -From the facts that we do not 
find them and that the variation in size among those which we are able to 
distinguish by certain definite characteristics is limited, we must infer that 
the young of all or most of these species associated together in different 
localities from those where the mature individuals are now found. Probably 
some such nurseries of the Triassic fishes will yet be discovered and will 
help the paleontologist of the future to discriminate between the species, 
but we must conclude that in the material now before us we have only 
mature or submature fishes, and this gives a probability to the distinctions 
we now make. Where we find twenty, fifty, or one hundred fishes which 
present common characters in size, outline, strength, shape of fins, ete, we 
may fairly conclude that these represent one species. Like all similar 
work, however, this must be considered as only provisional and liable to 
modification by the accumulation of more and better material. 
ISCHYPTERUS GIGAS, . sp. 
Pl. XIV, Fig. 3. 
Among the fish remains which were the fruit of many weeks of quarry- 
ing at Boonton a few fragments were obtained which belong to a species 
of Ischypterus much larger than any hitherto described. Unfortunately, the 
importance of these specimens was not appreciated by the quarrymen, and 
they did not take pains to preserve all the material which they brought to 
light. The remains of two individuals were found, both unfortunately 
much macerated and dismembered, the tails and posterior portions of the 
body, the most resistant parts, alone being well preserved. The heads and 
MON XIy——4 
