62 Salmonidae 



The stomach in all the Salmonida is siphonal, and at the 

 pylorus are many (15 to 200) comparatively large pyloric cceca. 

 The air-bladder is large. The eggs are usually much larger 

 than in fishes generally, and the ovaries are without special 

 duct, the ova falling into the cavity of the abdomen before 

 exclusion. The large size of the eggs, their lack of adhesive- 

 ness, and the readiness with which they may be impregnated, 

 render the Salmonida peculiarly adapted for artificial culture. 



The SalmonidcB are peculiar to the north temperate and 

 Arctic regions, and within this range they are almost equally 

 abundant wherever suitable waters occur. Some of the species, 

 especially the larger ones, are marine and anadromous, living 

 and growing in the sea, and ascending fresh waters to spawn. 

 Still others live in running brooks, entering lakes or the sea 

 when occasion serves, but not habitually doing so. Still others 

 are lake fishes, approaching the shore or entering brooks in 

 the spawning season, at other times retiring to waters of con- 

 siderable depth. Some of them are active, voracious, and 

 gamy, while others are comparatively defenseless and will not 

 take the hook. They are divisible into ten easily recognized 

 genera: Coregonus, Argyrosomus, Brachymystax, Stenodus, On- 

 corhynchus, Salmo, Hucho, Cristivomer, Salvelinus, and Pleco- 

 glossus. 



Fragments of fossil trout, very imperfectly known, are re- 

 corded chiefly from Pleistocene deposits of Idaho, under the 

 name of Rhabdofario lacustris. We have also received from 

 Dr. John C. Merriam, from ferruginous sands of the same region, 

 several fragments of jaws of salmon, in the hook-nosed condition, 

 with enlarged teeth, showing that the present salmon-runs have 

 been in operation for many thousands of years. Most other 

 fragments hitherto referred to Salmonidaz belong to some other 

 kind of fish. 



Coregonus, the Whitefish. The genus Coregonus, which in- 

 cludes the various species known in America as lake whitefish, 

 is distinguishable in general by the small size of its mouth, the 

 weakness of its teeth, and the large size of its scales. The teeth, 

 especially, are either reduced to slight asperities, or else are 

 altogether wanting. The species reach a length of one to three 

 feet. With scarcely an exception they inhabit clear lakes. 



