102 PALEOZOIC FISHES OF NORTH AMERICA. 
these great fishes have been found in Europe or America, and it is evident 
that no satisfactory comparison can be made between them until other parts 
of their structure shall be known. ‘To stimulate search for further and better 
material I have thought best to call attention to these great scales found by 
Mr. Sherwood and give figures of them. It will be seen by reference to 
these figures that our specimens are so much like those described by Agassiz’ 
that no character could be fixed upon which would serve to separate them 
specifically. I have, therefore, provisionally united them, leaving to those 
who shall be fortunate enough to find something more than these detached 
fragments to furnish unquestionable evidence of identity or difference. 
Only two species of Holoptychius are represented in our collections by 
portions of the body covered with scales in such numbers as to show the 
range of size and variation in markings. These are H. Americanus, Leidy 
and H. Hallii, Newb. The material permits these species to be fairly well 
defined. None of the scales are tuberculated, and hence they may be con- 
sidered clearly distinct from the fishes which bore the tuberculated scales, 
H. tuberculatus and H. giganteus? Whether the latter two species do not run 
together remains to be shown by future observations, but the scales of 
H. tuberculatus occur only in the Chemung, and judging from the specimens 
we now have are not more than half the size of those I have referred to 
HZ. giganteus. 
HELODUS GIBBERULUS, Ag. 
Among the fish remains collected by Mr. Beecher at Warren, Pa., are 
numerous small, polished, pitted teeth, consisting of a tumid, subconical, 
central dome, with a low, subsidiary tubercle on either side. These teeth 
I have been unable to distinguish from those received from Professor Agas- 
siz, representing his species H. gibberulus, from the Mountain limestone of 
Armagh, Ireland Similar teeth occur in considerable numbers in the 
Waverly, at the Miller farm, on Oil Creek, Pa., and in the Mountain lime- 
stone of Illinois and Indiana. 
With teeth so small and simple as these it would be unwise to insist on 
an absolute identity of species, but we may at least say that in our Che- 
1 Mon. Poiss. Vieux Gres Rouge, pl. 24, figs. 2-10. Gyrolepis giganteus Ag.: Poiss. Foss.,vol. 2, 
p. 175, pl. 19, fig. 13. 
