38 SCIENCE SKETCHES. 
look with distrust on the different species of Salmo 
are quite ready to admit those of Coregonus.” 
It seems to.me, however, that the variableness 
in Coregonus has been underestimated. The Amer- 
ican species at least are all fishes of wide range, 
varying considerably with their surroundings. 
None of the other species reach the size, or have 
the value as food, of our common white-fish. The 
species of Coregonus differ from each other in the 
form and size of the mouth, in the form of the 
body, and in the development of the gill-rakers. 
These differences have led to the establishment of 
about five sections, or subgenera, the extremes of 
which differ remarkably, but which gradually pass 
from one into another. Of the species, the follow- 
ing are among the most noteworthy: — 
Coregonus oxyrhynchus —the Schnabel of Hol- 
land, Germany, and Scandinavia — has the mouth 
very small, the sharp snout projecting far be- 
yond it. No species similar to this is found in 
America. 
The Rocky Mountain White-fish (Coregonus 
williamsont) has also a small mouth and project- 
ing snout, but the latter is blunter and much 
shorter than in C. oryrhynchus. This is a small 
species abounding everywhere in the clear lakes 
of the Rocky Mountains and the Sierra Nevada, 
from Colorado to Vancouver Island. It is a hand- 
some fish, and excellent as food. 
Closely allied to Coregonus williamsoni is the 
Pilot-fish, Shad-waiter, Round-fish, or Menomonee 
White-fish (Coregonus quadrilateralis). This spe- 
cies is found in the Great Lakes, the Adirondack 
