FISHES OP LAKE SUPERIOR. 361 



We have stated above, when speaking of the generic characters, 

 the reasons which have induced us to change the name of this 

 species, and to work out again its synonymy. Therefore, nothing 

 more remains to be said on this point, and we proceed to give a full 

 description of it, also comparing it with the above species, and regret- 

 ting that we have been unable to compare it in nature with the O. 

 Hudsonius. As described by Dr. Richardson, his (7. Forsterianus, 

 which is our Aurora, is rather compared with that species than 

 described in detail, and as these two species are very different from 

 each other, the comparison has not been made in its most minute 

 peculiarities. 



The body is subcylindrical, compressed. Its general form, less 

 thick and stout than in the preceding species, presents the same 

 regularity of outlines, and the same harmony of the regions among 

 themselves. The greatest height corresponds also to the anterior 

 margin of the dorsal, and forms the fifth of the whole length, the 

 caudal excluded ; this height forms five-sevenths of the greatest 

 thickness of the body, which corresponds to the immediate back of 

 the head. The diminution is gradual towards the tail. The head 

 forms exactly the fifth of the whole length, and it is of course con- 

 tained four times in that of the body, the caudal included. It is 

 almost as compressed as in the preceding species, but less rounded 

 on the upper surface, more elongated, more conical, and the rostrum 

 more prominent. The skull is, however, declivous. The nostrils are 

 very large. The position of the eyes, opposite the rostrum and the 

 margin of the operculum, has the same relations as in the preceding 

 species. The mouth is larger, and seems to be placed more back- 

 wards, on account of the developement of the nose, but the upper lip, 

 when we extend it, easily reaches to its extremity. The lips are 

 more developed, and covered with more prominent caruncles. The 

 two lobes especially are more extended, and are not at all attached 

 to each other on the maxillary symphysis, as they are in the preced- 

 ing species, being in this respect more independent of each other. 

 (PI. 2, f. 4.) 



The surface of the head is covered with a smooth skin, through 

 which the rows of pores open, upon the whole, similar to those which 

 we have described in the preceding species. 



