FISHES OF THE DEVONIAN AGE. 33 
Order PLACODERMI. 
Family CEPHALASPID. 
Genus ACANTHOLEPIS, Newb. 
Among the fish remains found in the Corniferous limestone are many 
tuberculated cranial or dermal plates which have a prevailing spatulate 
outline, but differing much among themselves in form and consistence. 
Some are thin, and have the appearance of large, unsymmetrical scales ; 
others are thicker, and are produced into points that sometimes become 
spines. The outer surface of all these plates is more or less tuberculated ; 
the tubercles in some of them being strong and closely crowded, in others 
sparse and fine. Whether these are body scutes or cranial plates remains 
to be shown by future discoveries. That they form part of a somewhat ex- 
tended series which compose a more or less complete coat of armor is shown 
by the fact that in some instances two or more are found in close contact 
and occupying their true positions as regards each other. The fishes that 
bore these defenses were evidently of large size, as the scutes which formed 
their tessellated armor are sometimes eight or ten inches in length by two 
inches in width. Other plates are smaller, elliptical, spatulate, or triangular 
in outline, and several forms have angles which are produced into spines. 
Until more material shall be obtained which may serve for the recon- 
struction of this remarkable fish it would be premature to make any posi- 
tive assertion in regard to its zoological relations. I may say, however, that 
judging from the specimens before me, Acantholepis was a Placoderm, having 
Acanthaspis as its nearest ally in the Corniferous sea; both presenting char- 
acters which indicate an intimate relationship with Cephalaspis. 
In a paper published some years since in the Bulletin of the National 
Institute at Washington, I described a number of fish remains obtained at 
Delaware, Ohio, by the late Dr. Mann. Among these three species of Ora- 
canthus were described, viz, O. fragilis, O. granulatus, and O. abbreviatus, all of 
which I now believe to be phases of the varied scutes of Acantholepis. Some 
MON XVI——3 
