Jordan and Evermann. Fishes of North America. 501 



The following analytical key will assist in the identification of the 

 varieties of Salmo irideus, which we are at present disposed to recognize: 



a. Scales well imbricated; upper ray of pectoral usually more or less spotted. 



6. Scales comparatively large, in 120 to 150 series; sides profusely spotted, both anteriorly 



and posteriorly, especially above the reddish lateral band. 



c. Scales decidedly large, in 120 to 130 series. Body elongate; no red under the throat; 

 eye large; anal rays 11 or 12. Brook forms mostly of small size; sea-run examples 

 occasionally large; confined to the streams of the Coast Range. 

 d. Mouth mode-rate; coastwise streams of California. IRIDEUS, 781. 



dd. Mouth very small; coastwise streams of Oregon and Washington. 



MASONI, 781a. 



cc. Scales medium, in about 140 series. Body rather deop; eye comparatively small; 



anal rays 10 or 11. Coloration dark, usually with many spots; a small dash of 



red usually prcsenfrat the throat. Size medium, weight 2 to 8 pounds. Streams 



of Upper Sacramento Basin, not running down to the sea. SHASTA, 781b. 



bb. Scales small, in 150 to 185 series; size large. 



e. Back profusely spotted, anteriorly as well as posteriorly; some red under lower jaw. 

 Kern River, California. GILBERTI, 78tc. 



ee. Back with the spots chiefly posteriorly; no red under the lower jaw. Upper Saora- 

 mento Basin. STONEI, 781d. 



aa. Scales very small and not well imbricated, in about 175 transverse series. Belly, lower 

 fins, and lateral band yellow; ventrals edged with pale; upper ray of pectoral unspot- 

 ted; black spots numerous. A small form found in the head waters of Kern River. 



AGUA-BONITA, 781e. 



781a. SALMO IRIDEUS MASONI (Suckley). 



(BROOK TROUT OF WESTERN OREGON.) 



The common brook trout of the tributaries of the lower Columbia and 

 of coastwise streams of Oregon and Washington is very similar to the 

 typical irideus and is readily distinguished from its associates, gairdneri 

 and mykiss, by its large scales. Compared with myUss, it is less slender, 

 the snout more rounded ; there is no red between branches of lower jaw; 

 there are no hyoid teeth, the maxillary is broader and shorter, the opercle 

 more evenly convex, and there are fewer spots below the lateral line ; the 

 red markings on sides usually coalesce into a red band. Scales 120-20 to 

 130-22. Size small, rarely weighing a pound. Puget Sound to southern 

 Oregon, in streams of the Coast Range ; locally abundant. Apparently 

 merging into the ordinary irideus southward, if indeed the two forms are 

 distinguishable. We know of no diagnostic character, but further com- 

 parison is needed. (" Named in honor of my good friend Governor Charles 

 H. Mason of Washington Territory, who has so frequently aided me in 

 adding to my collections specimens of great interest and value in various 

 branches of natural history." SucJcley.) 



Fario clarkii, GIRARD, Proc. Ac. Nat. Sci. Phila., 1856, 219; not of RICHARDSON. 

 Salmo masoni, SUCKLEY, Pac. R. R. Surv., xii, part 2, 345, 1860, Cathlapootl River. (Coll. 

 Capt. Geo. B. McClellan.*) 



* "I obtained this species at the Cathlapootl River, Aug. 2, 1853, and am indebted for it to the 

 skill of Capt. Geo. B. McClellan, as he took it with the artificial -fly at a time when they did 

 not readily bite at any bait." Suckley. 



