FISHES OF LAKE SUPERIOR. 365 



gin of the interoperculum, this bone being hidden behind the pre- 

 operculum. The branchiostegal rays, three in number, are flattened 

 and excessively thin, ahnost equal in form and in size, and slightly 

 arched. 



The dorsal fin is higher than long, and situated about on the middle 

 of the back. Its anterior margin is twice as high as its posterior. 

 The upper margin is straight. There are ten rays, of which the 

 anterior is short and undivided ; the bifurcation is repeated to the 

 third degree on the central rays. The caudal is long and furcated ; 

 the rays are twice bifurcated ; the largest only have slight indicar 

 tions of a three-fold division. The anal, placed behind the dorsal, is 

 broad, but less high than this latter; its margins are straight; it 

 contains eleven rays, of which two are rudimentary and undivided at 

 the anterior margin. Those of the centre show the traces of a 

 triple bifurcation. The ventrals, narrow at their base, extend con- 

 siderably at their circumference, which is rounded ; they are situated 

 before the dorsal, and contain eight rays, the first being simple, the 

 five following subdivided to the third degree. The pectorals, 

 narrower and more elongated than the ventrals, are inserted behind 

 the suboperculum at a small distance from this bone. There are 

 eleven rays ; the first does not bifurcate at all, though it is articu- 

 lated ; the six following are articulated on their last third only ; the 

 five remaining are very short. 



Br. 3 ; D. I. 9. A. II., 10 ; C. 4. I. 9. 8. I. 4 ; V. 8 ; P. 11. 



The scales are of medium size, and about equal on all regions of 

 the body. Their form is subcylindrical ; the concentric and radiating 

 strjoe are visible only under the microscope. The lateral fine is 

 shghtly inflected from the upper angle of the opercular apparatus 

 upon the abdomen, to rise again opposite the dorsal, and thence con- 

 tinues in a straight line towards the tail, following the middle of the 

 sides. 



The back is of a yellowish green, with the outlines of the scales 

 black. The upper surface of the head and the snout are of a darker 

 tint. The face, the opercular apparatus and the sides have a bril- 

 liant silvery reflection, with a more marked median band. There 

 are some reddish spots on the face and the opercular apparatus, 

 fading sometimes into a uniform reddish tint all over the head and 



