FRESH-WATER MALACOSTRACA OF ONTARIO 151 



SESSIONAL PAPER No. 39b 



Gammarus fasciatus Say. Fig. 4, b. 



(?) Gammarus sp. Nicholson, 1873, p. 500. 



Gammarus fasciatus Smith, 1874, p. 653, Weckel, 1907, p. 40. 



Generally distributed in shallow water, under stones and among weeds, etc. 

 It is probably our commonest Amphipod, although not found in as large numbers 

 as is Hyalella. It is found from Maine to Wisconsin on the north according to 

 Smith. 



Localities. — Lakes Superior and Michigan (Weckel). 



Georgian Bay : Waubaushene, Rattlesnake Harbour (Fitzwilliam Id.) (Wo) ; 

 McGregor Bay (Wiarton) (R). 



Lake Ontario: Toronto; Coburg (Wa). 



Niagara Falls (Weckel). 



Stomachs of Black Bass (Forbes). 



The characters of this species have been suflEiciently indicated in the keys. 

 Length up to 15 mm. 



r~\ 



Gammarus limnaeus Smith. Fig. 4, a. 



G. lacustris Smith, 1871, p. 453. 



G. limnaeus Smith, 1874, p. 651; Weckel, 1907, p. 42. 



This species is much less abundant than the preceding and occurs with it. 

 According to Weckel, it ranges from Maine to Utah. 



Localities. — Lakes Superior and Michigan (Smith and Weckel). 



Georgian Bay: Rattlesnake Harbour (Fitzwilliam Id.) (Wo). 



Stomachs of Trout (Smith). 



I have been unable to separate this species from the preceding, except in 

 regard to the presence or absence of bristles on the sides of the terminal segment 

 of the outer ramus of the last uropods. The number of joints in the secondary 

 flagellum of the antennule varies from 2 to 4 in G. limnceus and from 3 to 6 in G. 

 fasciatus. The other differences given by Weckel are only differences of degree 

 and not easily applied. Length up to 20 mm. 



