XXX AMERICAN FISHES. 
In the far north of America, and the Canadian Dominion generally, the 
characteristic fishes are of types common to Europe and America, such as 
the Graylings, the White-fishes, the Trouts and Chars, the Pikes, the Perch 
and Pike-perches, and the Cusk (Zofa). As we descend southwards, these, 
one by one, disappear or retreat to the highlands and lose their prominence, 
becoming subordinate to or replaced by forms peculiar to the continent. 
Those characteristic American fishes are numerous genera of Suckers or 
Catostomids, of Cyprinids, and of Sunfishes or Centrarchids. 
The peculiar American types have their headquarters mostly in the great 
Mississippi valley. Numerous representatives, however, and some peculiar 
genera, occur outside, especially in the southeastern States, but as we pro- 
gress northwards, they diminish in number, and in the northeast are so few 
that that section appears to be, to a certain extent, isolated, and was desig- 
nated nearly half a century ago by Agassiz as the “ zodlogical island of 
New England.” 
The streams discharging into the Pacific Ocean are deficient in the types 
characteristic of the greater part of the continent, having only one repre- 
sentative of the Centrarchids and no true Sunfishes or Black Basses. The 
fish fauna is composed almost solely of the Sucker and Carp-like families, 
and the latter has many species of large size and corresponding economical 
importance. The species are most numerous and diversiform in California, 
and gradually decrease northwards. 
The extent to which the various species are collocated or segregated has 
determined some naturalists to partition the continent into a number of 
geographical or faunal “regions ” or “districts.” These are more or less 
natural and expressive of facts of distribution, but for our present purpose 
a more useful and available division will be into two great areas, (1) the 
streams flowing directly or indirectly into the Atlantic Ocean and the Gulf 
of Mexico, and (2) those discharging directly or indirectly into the Pacific 
Ocean or the Gulf of California. 
(C) SaLtT-waTER FISHES. 
Salt-water fishes are distributed in an altogether different manner from 
those of the inland bodies of water. Instead of being segregated in conti- 
nents, or accommodated to the lay of the land, their range is determined 
largely by temperature. In the cold and icy waters of the north, ranging 
through the entire zone, the families of Herrings, Smelts, Sculpins, Cod- 
