116 PALEOZOIC FISHES OF NORTH AMERICA. 
portion is smooth, while the exposed part, forming from one-third to one- 
half the area, is occupied by a series of sharply defined thread-like ridges 
radiating from the central point. These ridges vary from ten to fifteen in 
number; are sometimes all simple and nearly straight; more frequently 
some of them are dichotomously forked. 
Seattered scales of this fish are not uncommon in the Catskill rocks, 
but no entire specimen has yet been found. Whether this really belongs 
to the genus Holoptychius remains to be proved, but it was evidently a 
closely allied Crossopterygian. 
The size, form, and markings of the scales are perhaps more like those 
of Glyptolepis than those of most species of Holoptychius, but we have as 
yet no evidence that Glyptolepis ever inhabited the waters of North America. 
This question will doubtless be solved by future discovery. 
Giypropomus Sayre, Newb. 
Plate XVIII, Fig. 1. 
Glyptopomus Sayrei, Newb.: Ann. N. Y. Acad. Sci., vol. 1, p. 189. 
Fish fusiform, about two feet in length by five inches in diameter; 
head triangular in outline, five inches in length and breadth; cranial plates 
unknown; under side of the head covered by two large sigmoidally elliptic 
jugular plates, bordered by a row of five (?) lateral jugulars, of which the 
anterior is linear in outline, broadest behind; the middle three are rhom- 
boidal; the posterior is spatulate and the largest of the series; the pectoral 
fins are elliptic in outline, narrow at the base, which is without fin rays; 
central portion covered with scales and bordered by a margin of rays that 
become longer toward the extremity; posterior fins unknown; scales rhom- 
boidal or quadrangular, smooth beneath, strongly marked on the outer 
surface with pits or short, curved, vermicular furrows divided by sinuous 
ridges. 
The only specimen of this fish yet found was taken from a quarry on 
the Susquehanna River, near the mouth of the Mehoopany, which supplied 
the stone fora dam on the former river. It was procured by a railroad 
engineer, from whom it passed into the hands of Mr. Robert H. Sayre, and 
