318 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



Yar. siscoTfet (Agassiz) J. &, G. — Siscoivet Salmon. 



Body sliort aud deep, covered with tliick skin, there being an exces- 

 sive tendency to the develoijment of fatty tissue. Head very short and 

 deep, its ujjper surface broad and short, covered by a skin so thick as 

 to compk^tely liide the bones; no distinct median carina. Mouth very 

 large, its gape narrower than in S. namaycush. Teeth weaker than in 

 8. namaycush; supi)k»mental bone also shorter and broader. Maxil- 

 lary a little more than half the length of the head. Caudal fin well 

 forked. Scales rather small, about 175 in the lateral line. Coloration 

 as in 8. namaycush, but usually paler; fin-rays the same. Lake Supe- 

 rior; abundant, bui; not yet found elsewhere. Very close to the preced- 

 ing, but differing in the shortness aud breadth of the bones of the head 

 and in the extreme fatness of the flesh. It is probably a local variety 

 rather than a distinct species. 



(Salmo siscoicet Agassiz, Lake Superior, 1850, 333.) 



** Vomer "witliont raised crest, the clievron only being toothed; red-spotted. (Sal- 

 veliiius. ) 

 a Hyoid bone with a narrow median baud of teeth (sometimes lost). 



510. S. oqsiasScl (Grd.) Gill & Jor. — Oquassa Trout; Blue-hack Trout. 



Body elongate, considerably compressed, less elevated than in the 

 other species of this genus, the dorsal outline regularly but not 

 strongly curved. Head quite small, much smaller than in any other 

 of our trout, its upper surface flatfish. Mouth quite small, the maxil- 

 lary short and moderately broad, scarcely extending to the posterior 

 margin of the eye. Eye large, 3J in head. Jaws about equal. Scales 

 small, those along the lateral line somewhat enlarged. Pectoral and 

 ventral fins not elongate; caudal fin well forked, more so than in the 

 other species. Preopercle as in ;S'. fontinalis, but the lower limb more 

 developed; opercles without concentric strioe. Coloration dark blue, the 

 red spots small and round, much smaller than the pupil, usually confined 

 to the sides of the body; sides with traces of dark bars; lower fins varie- 

 gated, as in 8. fontinalis. Head 5; depth 5. D. 10; A. 9. Lat. 1. 230; 

 gill rakers about C -f 11. L. 12 inches. Smallest and handsomest of our 

 trout, as yet known only from the Kangeley Lakes, in Western Maine. 



{Salmo oquassa Girard, Proc. Acad. Nat. Sci. Phila. 1854, 262: Salmo oquassa GUuther, 

 Ti, 154; Jordan, Proc. U. S. Nat. Mus. i, 81.) 



511. S. naresi (Giiuther) Bean. 



Greenish above, sides silvery or deep red, with very small red spots, 

 much smaller than the pupil ; lower fins deep red, with the anterior 



