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 Schndbel 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 

 williamsoni) has also a small mouth and project- 

 ing snout, but the latter is blunter and much 

 shorter than in C. oxyrhynchus. 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 



