320 LAKE SUPERIOR. 



with scales as also the upper half of the operculum. The rest of 

 the opercular apparatus is bare. The preoperculum is harrow, its 

 posterior margin undulated. The operculum is trapezoidal ; its an- 

 terior margin concave ; the postei'ior rounded, and the lower oblique. 

 The suboperculum, somewhat longer than the operculum, is about 

 one-third as broad, being, however, somewhat more narrow behind 

 than in front. The interoperculum is very narrow and elongated, 

 being undulated like the preoperculum on its outer margin. The 

 branchiostegal membrane is narrow ; it contains fifteen rays, of which 

 the first is much the broadest ; .all are flattened or compressed ; the 

 longest are two inches ; the shortest five-eighths of an inch long. 



The body grows thinner towards the tail from the ventrals, under- 

 going a considerable contraction behind the dorsal and anal fins. It 

 widens again at the insertion of the caudal. 



The dorsal fin has a quadrangular form, its upper margin being 

 only slightly arched ; it is two and three-eighths inches long and two 

 inches high. The rays are twenty-one in number ; the three first are 

 very short, and are apphed towards the fourth ; the three last diminish 

 equally in height ; its posterior margin is at a distance of three inches 

 from the rudimentary rays of the caudal. The anal is situated a 

 little farther back than the doi*sal, at a distance of two and three- 

 eighths inches only from the basis of the caudal ; its circumference is 

 rounded ; there are ten rays ; the four first near the fifth ; its length 

 is an inch and six-eighths, its height two inches, making it, of course, 

 higher than long. The caudal is composed of eighteen rays ; it is 

 notched ; the breadth at the extremity of the two lobes measures 

 three and a half inches ; the largest rays correspond to the middle of 

 each lobe ; they are two and six-eigliths inches long, whilst in the 

 centre they are scarcely one inch and a half ; very small interradial 

 scales extend over a space of three-fourths of an inch for each lobe 

 from their insertion. The ventrals contain eleven rays ; they are 

 somewhat nearer the anal than the pectorals are, and also nearer to 

 the head than to the extremity of the caudal, being situated at ten 

 and six-eighths inches from the snout ; the whole length being nearly 

 one foot eight inches ; their form is broad and rounded on the outer 

 circumference ; their insertion measures about five-eighths of an inch, 

 their greatest breadth one inch and a fifth, and their length two 



