314 LAKE SUPERIOR. 



magnifying glass, traces of fine denticulations may be discerned at 

 its inner margin. 



D. IX-10 ; A. 9 ; C. 4. 12.4 ; P. 10 ; V. I. 1. 



The body, besides the bones of the belly, is completely bare and 

 unprovided with scales. On the sides of the tail we remark a small 

 carina, which extends from the hinder third of the dorsal and 

 anal fins to the basis of the caudal. This carina is formed by 

 small bon}^ pieces, upon which rise small depressed hook-like points. 

 The lateral line is continued from the anterior extremity of this 

 carina to the occiput, following the back-bone. 



This species has been found in abundance at the Pic. Wlien alive, 

 its color is of an olive brown above, mottled with blackish brown and 

 silvery white below. 



Gasterosteus ptgm^us, Agass. 



Plate IV., fig. 1. 



This species is very inferior to the Gr. concinnus in its size, so that 

 we have in it, and not in this latter, the true pigmy of the genus. 

 Its length does not attain eleven-sixteenths of an inch. The head, 

 measured from its anterior extremity to the posterior margin of the 

 operculum, has a little more than one-fourth of it. Its height varies 

 between one-seventh and one-eighth of an inch, and remains nearly 

 the same from the nape of the neck to the anterior fourth of the dorsal. 

 The eyes are proportionally large ; the nostrils, situated at the upper 

 margin of the orbits, occupy the middle of the space between this 

 latter and the end of the snout. The head is somewhat sloping. 

 The curve of the back, very elliptical on its middle, descends abruptly 

 towards the tail about the insertion of the soft dorsal ; that of the 

 belly is slightly convex, and ascends also very abruptly, to form, in 

 conjunction with that of the back, a narrow contraction on the middle 

 of the peduncle of the tail, which is remarkably short, measuring 

 scarcely one-eighth of an inch from the posterior margin of the 

 dorsal and anal fins to the origin of the caudal. The anus is placed 

 seven-sixteenths of an inch from the head. The body is completely 

 bare ; the bones of the head are smooth ; the opercular apparatus 



