76 REPORT OF STATE BOARD OF FI8H COMMISSIONERS. 



the cavity of the abdomen before exclusion. The large size of the eggs, 

 their lark of adhesiveness, and the readiness with which they may be 

 impregnated, render the Salmonidse peculiarly adapted for artificial 

 culture. 



The Stihno)ii(bc are peculiar to the North Temperate and Arctic 

 regions, and within this range they are almost equally abundant wher- 

 ever 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 enter- 

 ing brooks in the spawning season, at other times retiring to waters of 

 considerable 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: CoregonuH, Argyr- 

 osovius, Plecoglofi^us. Brachymystax, Stenodus, Oncorhynchus, Salmo, 

 Hvcho, Cristiromer, and Salvelinus. 



Fragments of fossil trout, very imperfectly known, are recorded 

 chiefly from Pleistocene deposits of Idaho, under the name of Rhabdo- 

 fario larvstrifi. We have also received from Dr. C. Merriam, from ferru- 

 ginous sands of the same region, several fragments of jaws of salmon in 

 the hook-nosed condition, Avith enlarged teeth, showing that the pres- 

 ent salmon runs have been in operation for many thousands of years. 

 Most other fragments hitherto referred to Salmonidse, belong to some 

 other kind of fish. 



Oncorhynchus, the Quinnat Salmon. — The genus Oncorhynchus 

 contains the salmon of the Pacific. They are in fact, as well as in 

 name, the king salmon. The genus is closely related to Salmo, with 

 which it agrees in general as to the structure of its vomer, and from 

 which it differs in the increased number of anal rays, branchiostegals, 

 pyloric coeca, and gill-rakers. The character most convenient for dis- 

 tinguishing Oncorhynchus, young or old, from all the species of Salmo, 

 is the number of developed rays in the anal fin. These in Oncorhynchus 

 are thirteen to twenty, in Sahno, nine to twelve. 



The species of Oncorhynchus have long been known as anadromous 

 salmon, confined to the North Pacific. The species were first made 

 known nearly one hundred and fifty years ago by that most exact of 

 early observers, Steller, who almost simultaneously with Kraschen- 

 innikov, another early investigator, distinguished them with perfect 

 accuracy under their Russian vernacular names. These Russian names 

 were, in 1792, adopted by Walbaum as specific names in giving to 

 these animals a scientific nomenclature. Five species of Oncorhynchus 

 are well known on both shores of the North Pacific, besides one other 

 in Japan. These have been greatly misunderstood by early observers 



