74 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



moderate, comparatively thin and loose, appearing silveiy, espe- 

 cially in fishes -which have entered the sea: tins small, the last raya 

 of the dorsal somewhat elongate, the first ray usua^y less than 

 twice the height of the last ray ; caudal fin slightly forked, or more 

 usually truncate, with a slight emargiuation, double-rounded when 

 spread open : upper parts, especially the back, and the dorsal and 

 caudal fins, more or less thickly covered with small, rounded, black 

 spots ; in some specimens, especially those which have been in the 

 sea, these spots are more or less confluent, obscured or eveu obsolete : 

 species not of the largest size, the sexual peculiarities not strongly 



marked (Subgenus Salar.) 



a. Hyoid bone entirely destitute of teeth. 



I. Scales comparatively large, in 120 to 150 transverse series, 

 c. Body more or less short and deep, compressed, the depth .24 to .33 of length. 

 Head short, bluntish, convex above, obtusely carinate, about .25 of 

 length : mouth small, smaller than in any other of the group, the 

 maxillary bone of moderate width, scarcely reaching beyond the 

 eye, .10 to .11 of length, the mandible about .15: eye large, about 

 .05 of length : caudal fin moderately but very distinctly forked, 

 more so than in any of the other members of the group ; first long 

 ray of dorsal about twice the height of the last ray: dorsal, 2, 11; 

 anal, 2, 11 : scales a.bout 28-135-28, varying considerably, but in all 

 cases decidedly larger than in any other of our species of tSalar. 

 Rivers from California to British Columbia west of the Sierra 

 Nevada irideus. 



hb. Scales comparatively small, in 165 to 205 transverse series. 



d. Caudal fin somewhat forked: head rather small, about .25 of length, pointed 

 and lengthened, conical, the upper outline rather narrow and not 

 much convex, the carina slight : mouth moderate, the maxillary 

 comparatively narrow and extending much beyond the eye : opercle 

 considerably prolonged backward : scales small, 28-180-29 : depth 

 about .24 of length : body nearly equally spotted before and behind. 



Rivers wes*; of Sierra Nevada tsuppitch. 



dd. Caudal fin double-rounded or truncate, not at all forked in the adult, 

 e. Head not notably broad and flat, heavy and proportionally short, its 

 upper outline strongly convex, both longitudinally and trans- 

 versely : mouth very large, the maxillary extending much past the 

 eye in the adult, the opercle not especially prolonged backward: 

 dorsal fin notably high behind, its last rays more than f the height 

 of the first, some of the middle rays shortest: scales small: depth 

 of body about .24 of length : spots on body most numerous poste- 

 riorly. Rocky Mountains to the Sierra Nevada south of the Colum- 

 bia region spilurus. 



X. Scales medium, in 170 to 190 transverse rows : top of head gibbous, 

 obtusely carinated. Headwaters of Rio Grande, Bear River, etc. 



Subspecies sjnlurus* 

 XX. Scales small, in 190 to 205 rows : head more or less sharply cari- 

 nated, much less gibbous. Generally distributed. 



Subspecies pleuriticusA 

 aa. Hyoid bone with an elongate band of small teeth between the bases of the first 

 and second pairs of gill-arches (readily scraped ofi" by careless 

 observers, and possibly sometimes naturally deciduous). 



* ,'^almo fipilurus Cope, 1872.— Salmo stomias var. spilurus Jordan, 1878. 

 t Salmo pleuriticus Cope, 1872.— Salmo stomias var. pkuriticus Jordan, 1878. 



