xlviii AMERICAN FISHES. 
FAMILY OF SCLENIDS OR CROAKERS. 
Aplodinotus grunniens: Fresh-water Drum or Sheepshead; Gaspergou. 
(Haploidonotus grunniens, p. 142.) 
(B) FResH-WaTER FIsHES OF THE PaciFic SLOPE. 
The transmontane fish fauna is preéminent for the fewness of the families 
and paucity of specialized American types. There are, in fact, with the 
exception of one Percopsid in the Columbia River, no representatives of 
most of the families which give the stamp of peculiarity to the Union’s 
population ; the Etheostomine and indeed all other Percids are wanting, 
and only a single species of Centrarchids—the Perch of the Sacramento 
(Archoplites interruptus)—has found its way across the mountains. The 
most interesting of the spiny-rayed fishes is a much modified representative 
of the singular family of viviparous fishes or Embiotocids, whose many 
species otherwise are marine. The other spiny-rayed fishes belong to the 
families of Sticklebacks or Gasterosteids and Cottids. These are shared 
with Europe and the north and east, and are of no economic importance. 
The dominant families are the Catostomids and the Cyprinids, and of these 
there are many species and many specialized transmontane types. An 
especially noteworthy fact is the large size to which many of the Cyprinids 
attain. They thus contrast strongly with the small representatives so abun- 
dant in cismontane waters, and compare well with kindred of European 
streams. 
The Salmonids of the interior and mountains of this region manifest 
numerous variations, and the expression of those variations in systematic 
terms is difficult. Jordan and Evermann, in their “ Synopsis of the Fishes 
of North and Middle America” (1896), recognized only three species 
(mykiss, gairdneri, and irideus), but named many varieties or “ sub-species,” 
to which they gave trinomial names. In 1902, however, they raised those 
sub-species to full specific rank. The former view seems to be that most 
convenient and instructive to the angler and practical man—for the 
present at least—and consequently has been retained. The question is 
involved in too many technical difficulties to be considered here. 
The fresh waters of this region are the sources of supply of one of the 
great fisheries of the world by reason of the immense schools of Salmons 
which annually ascend the rivers to spawn. Those of the greatest econom- 
ical value belong to a genus peculiar to the North Pacific named Oxcorhyn- 
chus, and its five species are common to both sides of that ocean and the 
