FOSSIL FISHES. 65 
dant; one slab of shale formerly belonging to the Lyceum of Natural His- 
tory, though scarcely more than a foot square, carried impressions of over 
twenty individuals. 
Genus PTYCHOLEPIS Ag. 
Fusiform, tile-scaled ganoids of moderate size, from six to twelve inches 
in length; head pointed; fins all delicate and provided with minute fulera, 
dorsal triangular in outline placed near the center of the back, pectoral fins 
pointed, anal fin nearer to the tail than to the ventrals, caudal but slightly 
heterocercal; the posterior extremity of the body oblique, longer, and 
rounded on the upper side; scales quadrangular, generally much longer 
than high, and traversed by furrows which divide the surface into ridges or 
folds that suggested the name; the posterior margin of the scales notched 
by the extremities of the furrows; head bones all highly ornamented with 
raised lines of enamel; teeth small, conical, acute. 
Agassiz first described this genus (1843) from specimens found in the 
Lias at Boll, in Wiirtemberg. The type he called Ptycholepis Bollensis.* 
This was a fish about a foot in length, which has been met with in England 
and at several places on the Continent of Europe. In 1852 Sir Philip Eger- 
ton described another and much smaller species, which he called P. minor, 
obtained from the Lias at Barrow-on-Soar.* In 1853 he described and fig- 
ured still another species very much broader than the last, and called it P. 
curtus.? The specimen upon which this description was founded was from 
the Lias near Lyme Regis. 
In 1878 8. W. Loper, of Durham, Conn, found in the Triassic beds, 
which have yielded so many fishes at that locality, several specimens of still 
another species of Ptycholepis, which came into my possession and were de- 
scribed in the Annals of the New York Academy of Sciences, volume 1, 
p. 127. Since that time perhaps a dozen more or less complete individuals 
of this species have been obtained at Durham by Mr. Loper, all of which 
have passed under my observation. They vary considerably in size, the 
largest being eight inches long by two and a half broad; the smallest about 
' Poiss. Foss., vol. 3, p. 107, pl. LVIII bis. 
*Mem. Geol. Survey, United Kingdom, British Organic Remains, Decade 6, 1852, pl. VII. 
’Ibid., Decade 8, 1855, pl. VIII. 
MON XIV——5 
