NO. 180I 



MILLERS-THUMB AXD ITS HABITS GILL 



105 



spinescence, and the size of some of the rays as well as the size of 

 the body. Males appear to attain a larger size than the females, 

 although the reverse is claimed by some.^ All such probable differ- 

 ences, however, require confirmation and may vary apparently with 

 the species. 



The best observations on habits have been made on the Cottus 

 gobio of Europe and the Cottus gracilis of the United States. The 

 most notable on the former have been published by Newman, Heckel 

 and Kner, Fatio, and Smitt ; for the American species the best have 

 been made known by S. F. Baird and Simon H. Gage ; by the latter 

 in "Notes on the Cayuga Lake Star Gazer," in "The Cornell Review" 

 for 1878, pages 91-94, which merit exhumation from the obscurity 

 in which they were buried. 



IV 



The species, numerous as they are, probably differ very little from 

 each other in habits. All are inhabitants of fresh waters, though not 

 all absolutely confined to such, and most of them of clear, cold 



4 



Fig. 32. — Cottus gracilis female. After C. viscosus Girard (Sonrel). 



streams or lakes with a stony or rocky bottom. When in lakes, they 

 aft'ect the mouths of streams discharging into them. They are soli- 

 tary most of the time, although where one is found, others may be 

 lurking not far away. 



S. F. Baird, who explored extensively the fresh waters of the 

 northern United States in the early years of his life, summarized 

 (1851) the results of his investigations of the most common of the 



^ My own observations have led me to believe that the male may attain a 

 larger size than the female. Such was also represented to be the case by 

 J. L. Prevost (1825). Fatio, a most careful observer, however, thought that 

 the female was generally larger; he specified (p. 116) : "Males presentant une 

 tete plus largement arrondie en avant, avec une taille volontiers un pen 

 moindre que celle des femelles." It is apparently a case of averages. 



