78 UNIVERSITY OF COLORADO STUDIES 



in full color are quite distinct. Occasionally long slim individuals known as 

 " Racers " are caught, the coloration of which is strikingly peculiar in some respects. 

 A large racer with a bright red stripe along each side of the body below the lateral 

 line was recently reported to the writer from Grand Lake. In using the key the 

 red blotches due to the breaking-up of the lateral red band are not to be confused 

 with the bright-red, well-defined spots of the Eastern Brook Trout and the Brown 

 Trout. Parr marks are to be disregarded unless mentioned. The scale cross- 

 rows mentioned below refer to the oblique bands of scales which cross the body 

 dorso-ventrally. These bands should be counted from the gill opening posteriorly 

 to the base of the caudal fin, and may best be followed just above the lateral line. 

 The scales in the lateral line are not to be counted unless mentioned specifically. 

 Both color and anatomical characters are given, the more important of each 

 being italicized. The species groups followed are those of Jordan.' 



a. Pyloric coeca 65 or more; scales large, about 120 in the lateral line and 23 between the base of the 

 dorsal and the lateral line; vomer feebly toothed; color above brownish, sides silvery with numer- 

 ous black spots some of which are almost as large as the pupil of the eye, but without red spots; 

 five or more large, black spots on the operculum; sides of the body in breeding males with several 

 suffuse reddish patches; no red on the throat near the inner edge of the lower jaw; dorsal, ventral 

 and anal fins not tipped with white or yellowish; young with 1 1 or more parr marks; breeding 

 males with the lower jaw hooked; flesh salmon red; tail without black spots. 



S. sebago Girard, "Landlocked or Sebago Salmon" 

 aa. Pyloric coeca 40 to 60, usually about 45; vomer strongly toothed; 120 or more cross-rows of scales; 

 parr marks of the young usually less than 1 1 ; tail with black spots. 

 b. Sides without red spots, although red clouds or a lateral red band may be present. 



c. About 12} cross-rows of scales; general color dusky or greenish; sides of the body in the 

 lateral line region with a broad orange or red band, which is sometimes reduced to a series 

 of reddish clouds; body, head and fins with numerous, small, rather uniform, black 

 spots, which are especially close together dorsally and on the caudal and dorsal fins; 

 usually no red on the throat near the inner edge of the lower jaw; ventral, anal and dorsal 

 fins tipped with white or yellow; dorsal fin dusky, pectoral, ventral and anal fins more or 

 less yellowish or even orange; sides of the body below the lateral line often with a bluish 

 or lilac iridescence; scales of adults somewhat brassy. 



5. irideus shasta (Jordan), "Rainbow Trout" 

 cc. ISO to 200 cross-rows of scales; dorsal, ventral and anal fins not tipped with white or 

 yellowish. 



d. No red on throat near the inner margin of the lower jaw; about i$o cross-rows of scales; 

 general color silvery, bluish dorsally and quite blue on the top of the head and in 

 the mid-dorsal region; body above the lateral line, top of the head, dorsal and caudal 

 fins rather closely spotted with black; ventral and anal fins dusky. 



5. rivularis Ayres, "Steelhead Trout" 

 dd. A bright red mark on each side of the throat along the inner edge of the lower jaw, this 

 mark often somewhat concealed by the edge of the dentary bone but usually rather 

 prominent; scales small, usually 160 or more cross-series. 



e. Pectoral, ventral and anal fins red, reddish or pale, but not bright yellow; region along 

 the lateral line more or less reddish, often bright red. 



' Fishes (" Amer. Nature Series"), p. 319, 1907, New York. 



