DESCRIPTIONS OF GENERA AND SPECIES. 
SUBCLASS GANOIDET. 
ORDER LEPIDOSTEID®. 
FAMILY LEPIDOTIDZ. 
Genus ISCHYPTERUS Egerton. 
Under the names of Palconiscus fultus and Eurynotus tenuiceps two 
species of this genus were described by Agassiz.‘ Previous to that time a 
specimen had been sent from Massachusetts to M. Alexandre Brongniart, at 
Paris; this was examined by De Blainville, and was referred to his genus 
Palcothrissum, for which Palwoniscus was afterwards substituted. All these 
specimens lacked important parts, were distorted and imperfectly preserved; 
hence it is perhaps not surprising that their anatomical structure was misun- 
derstood, and they were included in genera to which they do not belong. 
Jurynotus is a paleoniscoid genus, restricted to the Lower Carbonifeious 
strata, having a different arrangement of the head plates, a high, broad 
dorsal, and a very heterocercal tail; features in which it differs essentially 
from the fishes now under consideration. Palaoniscus also has been clearly 
shown by Dr. R. H. Traquair, in his admirable studies of the family,” to be as 
distinctly separated from them. In 1841 Mr. W.C. Redfield published an 
article with the title “Short Notices of American Fossil Fishes.”* In this 
paper he describes five species of Palwoniscus, accepting the classification 
of Agassiz, who had referred them to this genus. These were P. fultus Ag., 
Poissons Fossiles (vol. 2, p. 43, pl. 8, figs. 4, 5; p. 159, pl. 14e, figs. 4, 5, 1833-1843.) 
?Quart. Jour, Geol. Soe., London, vol, 33, 1877, pp. 548-578, and Trans, Roy, Soc., Edinburgh, vol. 
29, pp. 343-391. 
Am. Jour, Sci., vol. 41, 1841, p. 24. 
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