III. COTTOIDS OF NORTH AMERIOA. 41 
least, as those of the latter can be deduced from the description of Sir John Richard- 
son, are as follow: Ist. A more backwards position of the vent. 2d. The lateral 
line which does not reach the caudal fin. 3d. The more advanced position of the 
anal relatively to the second dorsal; and, 4th, the shorter pectorals compared to 
the head. 
This species inhabits the northern shore of Lake Superior, where specimens 
have been collected by Dr. C. T. Jackson and Professor Agassiz, and are now pre- 
served at Cambridge (Mass.). A small individual of the same species may also 
be seen at the Smithsonian Institution. 
Ii. COTTUS COGNATWS, Ricu. 
Syn. Cottus cognatus, Riou. Faun. Bor. Amer. III. 1836, p. 40.—Hxeck. Ann. Wien. Mus. IT. 1837, 
p- 149.—Grirarp, Proc. Amer. Assoc. Ady. Se. II. 1850, p. 410; and, Proc. Bost. Soc. Nat. Hist. 
III. 1850, p. 189. 
This species we only know by the description of Sir John Richardson. This 
author compares it carefully with C. gobio of England, which we are told it 
resembles in numerous points. But this comparison will be valuable only after 
the C. gobio of all regions shall have been submitted to a severe criticism, and after 
we shall be satisfied of the identity or the difference of specimens collected in all 
the countries in Europe where that fish has been noticed. We have already 
mentioned the important fact observed by Mr. Heckel, that the C. gobio from 
Scandinavia belongs to a distinct species. 
The C. cognatus appears to have nearly the same dimensions as the C. gobio of 
England; the shape and size of the head are similar, but the mouth is larger. 
The head forms one-third of the length, the caudal fin excluded; its width is equal 
to its length ; its height is two-thirds of its breadth. The jaws are of equal length. 
The premaxillaries, the dentaries, and the vomer, are armed with short, velvet-like 
teeth. The tongue is smooth, broad, and short. The spine on the preopercular is 
small, curved upwards, and hidden under the skin. The branchiostegal rays are 
slender and cylindrical, as in C. Richardsonii, whilst they are stout and flattened 
in the C. gobio of England. The isthmus measures half an inch. 
The greatest depth of the body, taken at the origin of the first dorsal, corresponds 
nearly to the transverse diameter of the same region, whilst towards the insertion 
of the caudal, the thickness of the body is reduced to the half of its depth. The 
posterior part of the body is rather acute than rounded. The vent is a little 
nearer the end of the snout than the insertion of the caudal. The lateral line runs 
parallel with the back, to which it is nearer than to the belly. 
The origin of the first dorsal takes place a little behind that of the ventrals, at 
the same distance from the end of the snout as in C. gobio of England; but it 
extends more backwards, having two rays more,’ the largest of which measure 
1 Cuvier gives from six to nine rays fo the first dorsal of C. gobio; Sir John Richardson informs us that, 
as far as his observations go, he constantly found six spiny rays to the first dorsal, and sixteen articulated, 
6 
