FISHES OF LAKE SUPERIOR. 843 



of the orbit. The mouth is large in comparison to the other species ; 

 •when open, its form is that of a quadrangular tunnel, measuring 

 seven-eighths of an inch vertically, and one and three-eighths inches 

 transversely : it contains no teeth. But on the other hand, there are 

 two rows of rudimentary teeth on the tongue ; in order to see them 

 the membrane of the surface must be removed. The tongue itself is 

 narrow and pointed. The lower jaw is longer than the upper ; its 

 extremity is rounded and slightly raised. The intermaxiUaries are 

 small ; the maxillaries oblong and elongated, attaining, with their pos- 

 terior extremity, the anterior margin of the eyeball. The labials are 

 one half smaller, and of the same form, having a small point at their 

 anterior extremity. 



The outer circumference of the opercular apparatus is rounded and 

 semicircular, and scarcely shows a tendency to undulate in the margin 

 of the suboperculum. The operculum would be triangular were 

 it not for the curve of its upper and hinder margin ; the lower mar- 

 gin, contiguous to the suboperculum, is very oblique. The interoper- 

 culum attains the lower angle of the operculum ; its hinder angle 

 is rounded, subtriangular ; its anterior branch is completely covered 

 by the preoperculum, which is very wide at its angle. 



The branchiostegal apparatus is little developed, and arranged as 

 in G. clupeiformis. There are seven very close, short, and flat- 

 tened rays. 



The scales are proportionally large, easily falling off in individuals 

 fifteen inches long ; the largest are those covering the sides near the 

 lateral line', which measure six-eighths of an inch in the longitudinal 

 direction, and somewhat more than four in the transverse. On the 

 abdomen the proportions change ; they are somewhat higher than long, 

 and are sensibly oblong with their greatest diameter oblique. Beneath 

 the belly they are, as usual, much elongated. The lateral line is near 

 the middle of the body, somewhat nearer to the back than to the belly : 

 at its origin it rises above the operculum ; it is straight along the tail. 

 The termination of the scales on the caudal presents the same pecu- 

 liarity as in Q. clupeiformis. 



The dorsal is on the middle of the back, its height somewhat ex- 

 ceeding its length, and its upper margin straight. The adipose fin 

 is oblong, and elongated, exactly opposite to the hinder margin of the 



