54 MONOGRAPH OF THE FRESH WATER III. 
much less obtuse, and the mouth more deeply cleft. The eyes are subcircular; 
their longitudinal diameter is contained four times in the length of the head. The 
interorbito-frontal space is equal to the half of that diameter. The anterior 
nostrils are situated midway between the orbit and the extremity of the jaws; the 
posterior ones are nearer the orbits. 
The preopercular spine is hook-like, very acute, and different in all respects 
from that of C. viscosus. It resembles more that of C. Bairdii than any other 
species. The subopercular spine is slender and very acute. 
In spite of the great resemblance between the fins of this species and the pre- 
ceding one, a careful comparison shows that the paired fins are proportionally 
shorter. The base of the pectorals is slightly crescent shape; the tip of its rays 
scarcely reach the anterior edge of the second dorsal fin. The five uppermost rays 
do not overrun their membrane quite as much as exhibited in the figure. The 
ventrals are nearer the isthmus than in (. viscosus, and when bent backwards, they 
leave a greater space between their tip and the vent. Their insertion takes place 
immediately under the base of the pectorals instead of being situated behind. 
The first dorsal is nearly of the same height with the second; it is longer than 
in C. viscosus ; its upper edge is also more convex. ‘There are eight slender rays, 
the first and last being of equal size. The second dorsal is contiguous to the first, 
and terminates at a greater distance from the base of the caudal than in C. viscosus. 
It contains seventeen rays, or only sixteen, the last one, double. The caudal fin is 
posteriorly truncated, whilst it is rounded in C. viscosus. It forms nearly the sixth 
part of the total length. The origin of the anal is under the fourth ray of the 
second dorsal, and terminates under the thirteenth. When bent backwards the 
tips of the rays do not reach as far as those of the second dorsal. 
1830) a, 1D) vandt——ai, IN Dy (0) ih tk oe Ea a, WY QI ne 
All the rays are unbranched with the exception of two in the centre of the 
caudal, which, however, bifureate only once beyond the middle of their length. 
The vent is situated nearer the base of the caudal fin than the tip of the snout. 
The lateral line follows the curve of the back; it vanishes already under the 
sixth ray of the second dorsal, whence the series of minute pores is very little con- 
spicuous. Its fall near the tail takes place less abruptly than in C. viscosus. 
This species inhabits the southern and eastern shores of Lake Superior, where it 
has been collected first by Prof. James Hall of Albany, and afterwards by Prof. 
Agassiz, in whose cabinet specimens are still preserved. It is also to be seen in the 
collection of fishes at the Smithsonian Institution. 
The specimen figured is the largest we have seen. Its total length is three 
inches and one-sixteenth. 
