Til. COTTOIDS OF NORTH AMERICA. 
9 
cD} 
eda | 
Baird, about Carlisle (Pa.), in Mountain and Yellow Breeches Creeks, and Letart 
Spring, the largest of which were three and six-eighths of an inch. They all 
agree with the above description, excepting the color of an individual from Mountain 
Creek, which we found of a dark and uniform black. 
We owe to the kindness of Prof. S. S. Haldeman, an authentical specimen, three 
inches long, so that there can be no doubts left with regard to the species which is 
here described. 
The specimen figured was caught in the vicinity of Carlisle, and is preserved at 
the Smithsonian Institution, together with several others of the same vicinities. 
Specimens were also obtained from the Schuylkill at Reading (Pa.), and from the 
tributaries of the Potomac, at Rohrersville (Md.), and in Rock Creek, Washing- 
ton (D. C.). So that the range of ©. viscosus is Eastern Pennsylvania and Mary- 
land. 
EX. COPTUS FRANKELEINED, Acass. 
Puate II. Figs. 5 and 6. 
Syn. Cottus Franklinii, AGAss. Lake Sup. 1850, p. 303.—Girarp, Proc. Amer. Assoc. Adv. Se. II., 1850, 
p. 411; and, Proc. Bost. Soc. Nat. Hist. IIL, 1850, p. 189. 
Here is a species which we might easily have identified with the preceding, so 
much it resembles it by its general appearance, had we not looked into the ana- 
tomical as well as zoological peculiarities of both species. 
Before we were prepared to formulate distinctively the characters by which this 
species differs from its congeners, the form of the skull had already satisfied us that 
it was distinct. In the first place, and to speak only here of this species and of C. 
viscosus, which appear so much alike, the conformation of the skull has something 
so peculiar that, when once well understood, it will be easy to tell at first sight to 
which of these two species such and such skulls may belong (Compare Figs. 8 and 
12 of Plate III.). 
If the differences exhibited in those profiles are not specific, comparative osteo- 
logy can no longer be a sure guide in the study of species, nor can anatomy be 
of any help to zoology. But to this conclusion we have not yet arrived; we 
know what comparative osteology of the skull is worth, and, confident, in the future 
of that science, we should have established the two species as distinct on those 
characters alone. 
Zoologically speaking, the general form is short and stout. The greatest depth 
is contained five times and a half in the total length, and is proportionally greater 
than in C. viscosus. The least depth is one-ninetcenth of the length. The body 
tapers rapidly away, as in C. meridionalis and C. Alvordii. The peduncle of the 
tail is more slender, and the back more arched than in C. viscosus. The thickness 
is greater than the depth for a considerable length; towards the tail, however, the 
depth becomes greater. The body, as a whole, has rather a cylindrico-conieal 
shape. 
The head, proportionally shorter than that of C. viscosus, is contained two times 
and a half in the length of the body, the caudal fin excluded. The snout, also, is 
