No. 26.] ARTHEOSTRACA OF CONNECTICUT. I07 



Terminal uropods extending well beyond the first and second ; 

 first pair extending beyond second pair; rami of first pair over 

 half as long as peduncle and armed with spines; outer ramus 

 of terminal uropods made up of two joints; inner ramus not 

 quite as long as basal joint of the outer one which is very long. 

 Telson cleft to the base, the lobes being furnished distally with 

 two or three spines and a few cilia. 



Length 10-15 mm. 



This species has a wide distribution in the eastern and central 

 parts of the United States. It has been reported from Eastport, 

 Maine ; Hudson River and Niagara Falls, New York ; Lake 

 Superior ; Burlington, Iowa ; Lake Geneva, Wisconsin ; Washing- 

 ton, District of Columbia ; St. Johns River, Florida ; New Haven 

 and Woodbridge (near New Haven), Connecticut. 



It is abundant in fresh-water ponds among weeds and in 

 brooks under stones. 



Gammarus Fabricius. 



Abdominal segments provided with fascicles of spines dorsally. 

 Fiirst four pairs of coxal plates moderate, fourth pair the largest, 

 distinctly emarginated in its upper part. 



First antennae generally longer than second, provided with 

 well developed accessory flagellum. Second antennas rather 

 strongly built. 



Mouth parts normal. 



Gnathopods distinctly subchelate and more or less strongly 

 developed being always much more powerful in male than in 

 female. Pereiopods not greatly elongated. 



Last pair of uropods projecting beyond the others, with rami 

 spinous and setous, the outer one generally much the larger, and 

 having a small terminal joint. 



Telson rather small and cleft to the base. 



Gammarus locusta (Linnaeus). 



1894. Gammarus locusta, G. O. Sars, Crust. Norway, vol. i, 

 p. 499, pi. I and 176, fig. I. 



1906. Gammarus locusta, Stebbing, Das Tierreich, Lief. 21, 

 p. 476. 



