LAKE SUPERIOR. 



COTTUS. 



A broad and depressed head, contiguous to a body gradually 

 diminishing towards the tail, is the essential zoological character of 

 the genus Cottus, which contains at the same time freshwater and 

 marine species ; the former having, as the character of the group, a 

 head generally smoother and less prickly with spines than the 

 marine species, which in their turn are generally larger. 



Europe as well as America produces species of both groups. 

 For a long time all freshwater Cotti of central and northern Europe 

 were considered as identical with Cottus Grobio, when, twelve years 

 ago, Mr. Heckel * distinguished several species, very similar, it is 

 true, to Cottus Grobio, but differing, however, in many respects. 



Recently, an American naturalist has attempted to show that all 

 Cotti of Northern America constitute only a single species, and 

 that this species is identical with the Cottus Crobio of Europe. 

 However, studying the Cotti which we have collected around Lake 

 Superior, I first recognized two species ; then comparing them with 

 the C. cognatus Richards, and the C. viscosus Hald., I found these 

 two latter not only distinct from each other, contrary to the 

 opinion of Mr. Ayres, but yet distinct from those of Lake Superior. 

 So that the presence of C. G-obio in this continent is quite illusive, 

 as also the supposed identity of the Cotti in different regions. 



A monograph of the freshwater species of the genus Cottus in 

 Northern America would be a work of very great importance, were its 

 purpose but to rectify the different opinions entertained with regard 

 to them. 



Cottus Richardsoni, Agass. 



The largest individuals of this species which we have had at our 

 disposal, and on which our description rests, measure four and three- 

 fourths inches with the caudal. The head alone constitutes one 

 and one-fourth inches of this length, of course a little more than the 

 fourth part ; its breadth equals three-fourths of its length, and its 



♦Annalen des Wiener Museums, 1837, II. 



