FISHES OF LAKE SUPERIOR. 283 



It is composed of eighteen articulate, well-developed rays, measuring 

 two inches along the margins and one and eleven-sixteenths inches in 

 the middle of the fin, and of six raylets in the upper margin and 

 ten in the lower margin, hidden in the thickness of the skin. The 

 anal is high and rounded ; its insertion is two and a half inches 

 long. It numbers twenty-two rays ; those of the centre are one 

 and six-eighths inches high. The ventrals, one and three-sixteenths 

 inches long, are fan-shaped and rounded on their circumference ; 

 they have eight soft rays. The pectorals have almost the same 

 form, though less rounded. They are composed of seven soft rays 

 and one spinous, strong and robust, at whose inner side we remark 

 denticulations, varying in their number and form, and extending 

 only along the two upper thirds. The lower third has a carina with 

 a sharp blade. The length of the soft rays is one and three-eighths 

 inches ; the length of the spine one and three-sixteenths inches. 



The general formula of the rays is as follows : Br. 9 ; D. I. 6 ; 

 C. 18: A. 22; V. 8; P. I. 7. 



Besides the differences in the number of the rays, as we may esti- 

 mate by the numbers we have given above, this species differs farther 

 from the P. ccenosus and horealis in the general form of the fins. 

 Their position upon the body, relatively to each other, affords not less 

 sensible differences when we compare the measures which Dr. Bich- 

 ardson gives for his P. coenosiis, setting aside the difference of size 

 of our specimen, which had two inches more for its whole length. 

 Similar differences are remarked between our P. Felis and the P. 

 horealis, though for this latter we have not been able to make our 

 com})arisons upon positive numbers, the celebrated author having 

 neglected to give the numbers of the rays of this species. The pro- 

 portions and the dimensions of the head are also far from agreeing, 

 being in the P. coenosiis two-ninths of the whole length, and in 

 the P. borealis as broad as long, whilst we have seen, that in our 

 species its length forms the fourth part of the whole length, and 

 that besides, it is much longer than broad. The spinous ray of the 

 dorsal is more feeble than in P. camosus, and, besides, unprovided 

 with the deep groove in which the soft ray of this fin is lodged. The 

 spinous ray of the anterior margin of the pectorals, which in P. 

 borealis is unprovided with denticulations on its posterior margin, 



