264 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



tshowytscha 



gorbuscho 



ONCORHYNCHUS 



SJL VSLIHUS -CmSTfVOMCH 



Figure 18. — Diagrammatic comparison of genera based 

 on certain characters. 



It appears that Brachymysfax is the most primi- 

 tive and generalized of the genera, Hucho repre- 

 sents an intermediate stage, whilst Orworhynchus 

 is the most specialized. 



Table 33. — Numier of certain characters differing between 



genera of Balmonidae 



[Characters from table 32] 



SALVELINUS 



molma 



SUMMARY OF RELATIONSHIPS 



The foregoing material on hybridization, colora- 

 tion, anadromy, fecundity, morphological charac- 

 ters, et cetera, show the relationships between the 



Figure 19. — Suggested relationships among NorfJi 

 American Salmonidae. 



North American species of Salmonidae. In figure 

 19 the degrees of relationship have been indicated 

 by the relative distances between species. Since 

 many of the ditferences and similarities are difficult 

 to weigh with the information presently available 

 concerning the relative value of different criteria, 

 I have not attempted to be more precise. 



ANNOTATED KEY TO NORTH AMERICAN SALMONIDAE 



This annotated key is given in place of the more 

 conventional strictly dichotomous key. Keys are 

 used chiefly to determine the identity of a speci- 

 men, and each subdivision should not be inter- 

 preted as denoting relationships. 



The amount of information available varies 

 widely from species to species, but where avail- 



able, certain items (such as chromosome number) 

 have been included. Thus, although this section 

 has been arranged as a key, it is also a summarized 

 description of the North American Salmonidae. 

 It should be kept in mind that this paper is based 

 wholly on published data and that no attempt was 

 made to verify points that await further study. 



KEY TO GENERA 



A. Skeleton cartilaginous, very slight calcification: dorsal fontanelles closed in adults ; iwstorbitals contact preoperele ; 

 ascending process of premaxllla absent in adults; branehiostegal rays (left side) 10-19; gill rakers (first arch, 

 left side) 19-39; lateral-line scales 121-198; anal fin rays 15-22; pyloric caeca 55-249; dorsal fin rays 12-18; 

 vertebrae 62-75; only black spots or speckling at all ages (except breeding colors) ; ova and fry very large in 

 relation to adult size; anadromy obligatory or adaptive; mouth lining dark to black; all adults die after spawning. 



Genus ONCORHYNCHUS, Pacific salmons. 



AA. Skeleton fairly well calcified ; dorsal fontanelles persistent ; postorbitals do not contact preopercle ; ascending 

 process of premaxllla persistent; branehiost.egal rays (left side) 8-14; gill rakers (first arch, left side) 14-27; 

 lateral-line scales 105-138; anal fin rays 8-16; pyloric oaeca 20-170; dorsal fin rays 9-15; vertebrae 57-69; light 

 spots, !?pec-kling, or colored areas present at some stage; ova and fry medium to small in relation to adult size; 

 anadromy not adaptive or obligatory ; mouth lining white to black ; some adults may die after spawning. 



