114 PALEOZOIC FISHES OF NORTH AMERICA. 
identical with H. nobilissimus. Among Agassiz’s figures of the scales of 
Holoptychius in his Old Red Sandstone Fishes, are two very different kinds, 
which he combines, probably because he found them running together, 
under the name of I. giganteus. One? of these has almost precisely the 
ornamentation of the scales of H. Americanus; that is, a series of strong, 
flexuous, sometimes inosculating but subparallel ridges running from the 
interior to the posterior border. Another form, there represented by figs. 3, 
4, and 8, has most of the ornamented surface occupied by coarse, rounded 
tubercles; the middle portion only carrying short ridges mixed with tuber- 
cles. It is evident that we have here two strongly marked varieties, which 
without any great stretch of the imagination could be considered as dis- 
tinct species. This latter supposition is favored by the fact that in some 
cases the ridged type of scale referred to above seems to have covered the 
entire body, and I have seen similar scales from the Scotch Old Red Sand- 
stone nearly three inches in diameter. Precisely such scales as these, but 
never more than half as large, are common in the Catskill rocks, and repre- 
sent Dr. Leidy’s H. Americanus. Larger scales from the Chemung, nearly 
two inches in diameter, have a coarser ornamentation, consisting of mingled 
ridges and tubercles, and these I have made the type of a new species H. 
tuberculatus. 
Hoxoptycuius Haun, n. sp. 
Plate XX, Figs. 10-10*. 
Fishes, two to three feet in length by six to eight inches in width; 
head unknown; pectoral fins conical in outline, five inches long by two 
inches wide at base, pointed, acute, strongly lobed; central portion three 
inches long by half an inch broad, covered with scales and surrounded on 
all sides by a margin of fin rays; ventral fins midway between pectoral and 
anal; two dorsal fins, first dorsal opposite space between ventrals and anal, 
second dorsal slightly behind anal, both of these reaching back to caudal; 
caudal fin broadly triangular in outline; posterior margin nearly vertical, 
arched, about five inches in height in a fish 2 feet long; lower lobe very 
broad; prolongation of body turned upward and fringed on the upper side 
with rays about one inch in length; scales circular in outline, closely imbri- 
1 Mon. des Poissons Fossiles, etc. (Old Red Sandstone), pl. 24, fig. 2. 
