12 MONOGRAPH OF THE FRESH WATER IIT. 
tute a genus by itself, the genus Triglopsis associated there with a species of Cottus 
proper. 
Passing to the western coast of the American Continent, beyond the Rocky 
Mountains, between the latter and the shores of thé Pacific, we shall find in the 
Columbia River another species with a special combination of generic characters, 
the Cottopsis asper, associated with a yet undescribed species of Cottus proper, col- 
lected by the naturalists of the United States Exploring Expedition. The pub- 
lished ichthyology of that exploration will soon make us acquainted with other 
members of the Cottoid group. 
If we take a glance on a chart. at the localities of the North American Conti- 
nent where Cottoids have been observed, we shall find extensive tracts which still 
remain unexplored; all the country west of the Mississippi and Ohio, and in a 
northerly direction to Lake Superior. Then, again, the British Possessions, that 
region of numberless lakes, must contain some of these fishes, since we see that 
one species extends as far north-west as Great Bear Lake, the northernmost of all. 
Between Lake Superior, the mouth of the Columbia River, Great Bear Lake, 
and Labrador is included a vast area where Cottoids will undoubtedly be found 
hereafter, as well as within the limits of the western part of the United States, 
between the Mississippi and Ohio, to the shores of the Pacific. But how far south 
they occur we cannot yet tell with certainty. We know that fresh water Cottoids 
belong chiefly to the temperate zone, having been observed from the arctic circle to 
the 45° of latitude in the eastern hemisphere, and to the 35° in the western hemi- 
sphere. 
§ 4. Hasirs, Foop, anp Use. 
We have not had the satisfaction of observing ourselves the Miller's Thumbs of 
this continent in their natural medium. All authors agree in saying that clear 
and limpid waters with stony or sandy bottoms, are the places most preferred by 
these fishes. The small rivulets of cold water descending along the slopes of 
mountains are often their favorite residence, although likewise frequently inhabitants 
of large lakes. They keep sheltered under stones, which must be removed when 
in search of them. When uncovered, they sometimes dart away with great 
rapidity, in search of another hiding place; and sometimes they wait motionless until 
started. In Europe, there is scarcely a boy living in their vicinity who does not 
hunt them by uplifting carefully and slowly the stones of the shores of lakes, or at 
the bottom of rivulets, and transfixing the fish when motionless, by means of a 
fork attached to a stick. 
They are of little use to man, not to say in the economy of nature. The marine 
species are dreaded, being exterminated by fishermen, and generally thrown away 
when sufficiently mutilated. Sometimes, however, we see the head only cut off, 
and the body brought home for the table. The flesh of the fresh water species is 
delicate and much esteemed in some countries of Europe, where they occur in large 
numbers. Undoubtedly they would be much moressought for, if not generally so 
scarce and of a size too small to repay the trouble of hunting them. In fact, 
