FISHES OF THE CARBONIFEROUS SYSTEM. 105 
Crenacantuus RaNDALLI, 0. sp. 
Dorsal fin-spines twelve inches or more in length by one and a half 
inches in width at base of ornamented portion; form slightly curved back- 
ward, sides compressed, basal portion conical, smooth, or finely striated 
longitudinally ; line of demarkation between ornamented surface and base 
strongly marked, inclined downward and forward at an angle of 30° with 
the axis of the spine; ornamented surface near base formed by about forty 
fine, parallel, subequal, closely crowded ridges on each side of the median 
line, and these bear small, rounded, closely approximated tubercles. 
The basal portion of a large spine, showing about two inches of the 
ornamented surface, is the basis of the above description. This was ob- 
tained from the Olean Conglomerate, two miles northeast of Warren, Pa., 
by Mr. F. A. Randall. Several much more perfect specimens have been 
found in that vicinity, but they have been sent to Philadelphia and are not 
within my reach. Better material will be needed for a complete description ; 
but enough is shown in the specimen now described to prove this spine 
distinct from any other known. In the character of its surface markings 
this species resembles Ctenacanthus tenuistriatus, Ag. and Ct. speciosus, St. J. 
& W., but differs from both these in its narrower form and the character of 
the ornamentation of its surface. In C¢. tenwistriatus the ridges are separated 
by spaces as wide as themselves, whereas in the species under consideration 
they are for the most part contiguous or separated by very narrow furrows. 
In the former species also the ridges along the anterior border are much 
wider than on the sides, whereas in Ct. Randalli they are of nearly uniform 
size throughout. The tuberculation in the present species is very simple; 
rounded papillz, separated by spaces but little greater than their diameters, 
are set regularly along the summits of the ridges, while in Cf. tenwistriatus 
and in Ct. speciosus the tuberculation consists of transverse ridges, as is 
most common in the genus. 
The general aspect of this spine must have been similar to that from 
the St. Louis limestone described elsewhere in this memoir under the name 
of Ctenacanthus Littoni, but the ridges are in that species fewer and the 
tuberculation is much stronger and more crowded. 
