314 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



truncafus Siickley, Anu. Lye. Nat. Hist. N. Y. 18.58, 3: Salmo gairclneri Richardson, 

 Fanua Bor.-Amer. iii, 2'21: Salmo f/airdneri Sucklcy, Monogr. Salmo, 114: Salmo trun- 

 catus Glluther, vi, 122: Salmo gairdneri Giintlier, vi, llrt.) 



hb. Scales small, lGo-205 iu a lougitudinal scries. 



d. Caudal fiu truncate or double-rounded, not at all forked in tbe adult. 



507. S. spilBiB'HS Cope. — Eio Grande Trout. 



Bodj' elongate. Head heavy, but proportionately sliort, its upper 

 surface considerably decurved ; interorbital space transversely convex, 

 obtusely cariuated; the head more convex than in any other of our 

 species. Mouth very large, the maxillary reaching far past the eye. 

 Teeth on vomer in two distinct series. Dorsal fin low in front, high 

 behind, the last ray more than two-thirds the height of the first; last 

 ray of the anal rather long ; caudal with its middle rays about as long 

 as the others. Profusely spotted; back and sides with round black 

 spots, the spots most developed posteriorly, few on the head, most nu- 

 merous on the caudal and adipose fin; sides with pale blotches. Head 

 3J-; depth 4. D. 11; A. 10; scales 37-170-37. L. 30 inches. Upper 

 Eio Grande and Basin of Utah, frequenting mountain streams. 



(Cope, Haydeu's Geo!. Surv. Mont. 1871, 470, 1872; Jordan, Pioc. U. S. Nat. Mus. i, 

 74.) 



Var. pieurifiiciis (Cope) Jor. 



A more abundant and much more widely distributed form, having 

 the head and mouth equally large, but the top of the head less convex, 

 the median carina being more marked, especially in the young. The 

 scales are definitely smaller (39-200-40) and the coloration is rather 

 darker. This form abounds in all suitable streams from the Eio 

 Grande, through the Basin of Utah. Specimens intermediate between 

 spilurus and pleuriticus occur. 



(Salmo pleuriticus Cope, Hayden's Geol. Surv. Mont. 1871, 471, 1872; Jordan, Proc. 

 U. S. Nat. Mus. i, 74, 1878.) 



aa. Hyoid bone -vvitli a narrow band of small teetli (easily scraped off and very often 

 naturally deciduous, especially in old examples). 



50§. S. piirpuratus Pallas. — Salmon Trout of the Cohunbia; Yellowstone Trout; 

 llocky Mountain Brook Trout; Lake Trout. 



Body moderately elongate, compressed. Head rather short. Mouth 

 moderate, the maxillary not reaching far beyond the eye. Yomeriue 

 teeth as usual, set in an irregular zigzag series; teeth on the hyoid 

 bone normally present, but often obsolete, especially in old examples. 

 Dorsal fin rather low; caudal fin slightly forked, less so than iu irideus, 

 more than in S2nlurt(s (the caudal more forked in young individuals 



