FISHES OF THE YELLOWSTONE NATIONAL PARK. 11 



bluish or greenish olive, sides silvery with a varying number 

 of X- shaped or crescentic black spots; sides of head with 

 roundish black spots; tip of pectoral blackish; anal and tail 

 fins unspotted, varying much in coloration in different waters. 



Loch Leven trout, 5. 



hh. Scales in lengthwise series about 115 fully developed; 21 to 23 

 in oblique series from lateral line to upper base of ventral. 

 Color very variable but typically greenish olive on back, sil- 

 very on sides; belly white; irregular black spots on back and 

 sides; sometimes two rows on base of dorsal fin; none on tail; 

 variable number, but usually three or four roundish black 

 spots on gill cover. Young often with unocellated bright red 



spots along sides Landlocked salmon, 6. 



gg. Body comparatively short and deep; scales in lengthwise series 

 about 120, and about 30 in oblique series. Dark colored, olive 

 or brownish, with numerous irregular black or dark brown spots 

 above lateral fin below; usually ocellated red spots along side; 

 orange or yellow margin on upper part of dorsal and anal and 

 outer part of ventral. Light-colored young much resemble 

 young landlocked salmon but distinguished by the red spots 



having bluish areolas Brown trout, 7. 



dd. Scales in longitudinal series usually 200 or more. No black spots what- 

 ever. 



i. Scales in longitudinal series usually 200 or more (180-205); 

 never any ocellated red spots on sides; no rivulations on 

 back, dorsal fin, or tail. Tail always strongly forked. Colora- 

 tion extremely variable, generally grayish or yellowish gray, 

 profusely covered with round pale spots, sometimes almost 

 white, again deep orange, usually pale yellow; yellowish 

 spots on dorsal and partial dusky cross bars on upper and lower 

 basal half of tail. Young sometimes with faint mottling on 



. back slightly resembling the brook trout Lake trout, 8. 



ii. Scales in lengthwise series 215 to 23.0; red spots on sides always 

 ocellated with bluish; back usually yellowish gray and 

 always vermiculated or rivulated with dusky; dorsal and 

 tail with wavy dusky bars and rivulations; pectorals, ventral, 

 and anal reddish with white outer rays margined behind by 

 a narrow black streak. Coloration highly variable with age, 



locality, and season Eastern brook trout, 9. 



AA. No adipose fin; one or two dorsal fins. 

 a' ' . Dorsal fins more or less continuous, the anterior of spines or simple unjointed 



rays; the posterior of soft or jointed rays. 



b / . Anterior dorsal composed of strong sharp spines. General color, dark green 

 above, sides and belly greenish; an irregular blackish stripe along the 

 side from opercle to middle of base of tail, growing indistinct and disappear- 

 ing with age; three oblique dark stripes across cheek and gill covers; some 

 dark spots above and below lateral line. Coloration somewhat variable 



and quickly changeable Black bass, 10. 



W. Anterior dorsal composed of weak flexible spines or simple rays; small curved 

 hook at edge of gill cover. Coloration olivaceous, everywhere punctulate 

 with dark spots, conspicuous on top of head, four or five dark blotches on 

 back suggesting cross bars; dorsal, pectorals, and tail with wavy streaks and 

 series of spots; anal and ventral white, or sometimes dusky Blob, 11. 



