274 LAKE SUPERIOR. 



regular circle. They are quite as much inclined, and their hooka 

 are stronger, and more arched at the point. The radiating striae 

 are also more visible. 



In front of this double row of escutcheons and as if forming their 

 immediate continuation on the inner side of the pectoral fins, and 

 in front of them, we observe a subtriangular bone, the anterior 

 side of which is concave, bordering the branchial opening beneath. 

 These two bones are contiguous on their anterior angle, and form 

 by their reunion a convex curved line along the sides of the mouth, 

 to which the branchiostegal membrane is attached. A prominent 

 carina, but unprovided with hooks, extends along the median line 

 from the posterior angle. A single wrinkle indicates on the middle 

 of the anterior angle the rudiment of a carina. The striae radiate 

 from those two centres. The bone of the anterior part of the pecto- 

 rals and upon which these fins articulate, is small and hidden under 

 the skin. 



An odd elliptical escutcheon with regular outlines is situated in the 

 middle of the space between the anus and the anal fin. It has a slight 

 median carina, over which projects an elliptical hook. A rudiment 

 of an escutcheon leans towards the anterior margin of the anal. 



The anus opens in a small depression immediately behind the 

 ventrals, at a distance of about two-thirds of an inch from their pos- 

 terior margin, and one inch and three-sixteenths from the anterior 

 margin of the anal. It is small and surrounded by a cutaneous 

 membrane, bilobed on the posterior side. 



The skin over the whole space which the escutcheons do not 

 cover is rough to the touch. Small tubercles with acute points 

 cover uniformly its surface, being every where of equal size 

 and at an equal distance from each other. On the terminal arch 

 of the tail they become lengthened and flattened, and invest 

 the whole space like scales. 



The fins are generally small ; the dorsal, broader than it is 

 high, is triangular with the upper margin concave. It is com- 

 posed exclusively of soft rays, with the exception of a fulcrum 

 situated on its anterior margin. The rays are articulated and 

 subdivided only at their extremity. 



The upper lobe of the caudal is formed of small bony rays, short 



