176 PALEOZOIC FISHES OF NORTH AMERICA. 
seem to have been of delicate structure, and their preservation is somewhat 
unsatisfactory. The most siriking feature presented by these fishes is the 
long cylindrical body, which is generally found lying upon the back with the 
pectoral fins broadly extended. These are remarkable for the great number 
of fine bony rays which traverse them, and which seem to have been rarely 
jointed. The habits of this fish were undoubtedly carnivorous, and judging 
from the long pointed head and slender body it must have been very swift 
in its motions. The affinities, as has been mentioned, are probably with 
Paleoniscus, but it differs from all the species of that genus in the absence 
of fulcra from the pectoral, anal, and perhaps the dorsal and caudal fins. 
ASTEROPTYCHIUS ELEGANS, Nl. sp. 
Plate XXYV. Fig. 4. 
Spine six inches in length by four lines wide in the broadest portion 
lower half nearly straight, upper portion gently curved backward; basal 
or buried portion about one inch in length, conical in form, finely and 
irregularly striated; angle between plain and ornamented surface 45°; 
section a compressed triangle; enameled portion traversed by strongly 
marked, continuous, arched, and smooth ridges, eight in number at the base, 
six within an inch of the summit. These ridges are separated by narrower 
furrows which are longitudinally striated, and toward the summit each is 
set with a row of tubercles; posterior angles bearing relatively strong 
denticles throughout nearly the entire length; above, these are hooked 
downward; in the lower part of the spine they are triangular. 
Of this beautiful spine I have two specimens, of which one is quite 
complete. It is remarkable for the symmetry of its form and elegance of 
its ornamentation. It would doubtless be classed by all paleontologists as 
a species of Asteroptychius, and may perhaps serve as a fair representative of 
that genus, although the longitudinal ribs are relatively wider and the fur- 
rows much narrower than in the type. Of described species it is perhaps 
most like A. St. Ludovici, St. J. & W.,' the size and form being nearly the 
same, but it may be at once distinguished from that species by the teeth, 
1 Geol. Survey Illinois, vol. 6, p. 437, pl. 16, figs, 3-48, 
