366 LAKE SUPERIOR. 



shoulders. The iris is gold-colored ; the fins are of a uniform color, 

 a transparent, pale yellow. 



Fig. 1 represents the fish of natural size. Figs. 2 and 3 are en- 

 larged, to show the characters of the mouth and the jaws. 



This species is very common at the Sault of St. Mary ; specimens 

 were also obtained from the Pic. 



GoBio PLUMBEUS, Agass. 



This species is widely distinct from G-oUo cataractce, the only 

 species of that genus found in North America which has hitherto 

 been described. The body is elongated, subcylindrical, compressed ; 

 its greatest length is about seven inches. The head is contained 

 somewhat more than four times in this length, and the height of the 

 body forms exactly the fifth of it. The back is very slightly convex; 

 the belly describes a very marked curve ; the tail beyond the anal fin 

 straightens almost abruptly. The head itself is conical, irregularly 

 quadrangular, the upper surface being very flattened, sometimes 

 even concave on the middle line, and the lower surface plain. The 

 eye is situated at the upper region of the face ; its diameter is one 

 fourth of an inch. The nostrils are large also, and situated in circu- 

 lar cavities at the upper part of the face. The anterior opening 

 is oblong ; its canal is obUque from behind forwards ; its posterior 

 margin, when extended, forms a cover to the second opening, which 

 is the largest, perforated like the first, and placed a little more out- 

 wards. The snout is flattened. The upper jaw exceeds the lower, 

 and thus removes the mouth to the lower side of the head- At the 

 angles of the mouth there is a very small barbel, still more slender 

 than in the Gr. cataractce. It needs a very attentive examination to 

 notice it. 



The posterior margin of the operculum is notched in the form of a 

 small crescent at whose margin is a process of this bone. The lower 

 margin is oblique and shghtly concave, bordered on its whole length 

 by the suboperculum, a small, thin, narrow and elongated lamina. 

 The interoperculum and the preoperculum are hidden beneath the 

 fleshy skin of the cheeks. The branchiostegal membrane contains 

 three rays ; it is continued upon the opercular valve. 



