No. 26.] ARTHROSTRACA OF CONNECTICUT. 23 1 



Second pair of antennae elongate. 



Epimera very small or obsolete. 



Abdominal segments all fused together forming a broad, 

 shield-like plate. 



Mouth parts normal ; maxillipeds furnished with an epipod 

 and five-pointed palp. 



ASELLID^,. 



Body broad, depressed. Head without rostrum. Caudal 

 segment large, shield-like. Eyes small, lateral. 



Antennae with multiarticulate flagella; superior pair much 

 smaller than inferior pair. 



Mouth parts normal. 



Pereiopods ambulatory, except the first pair which are sub- 

 chelate. 



Pleopods, four pairs in female ; the first very small, not oper- 

 culiform; the three succeeding pairs biramous and lamelliform; 

 the outer ramus of second pair forming an operculum. In male, 

 five pairs of pleopods, an additional one between the first and 

 second forming the copulatory organs. 



Uropods large, biramous, with rami styliform or lamellar. 



Asellus communis Say. 



1818. Asellus communis, Say, Jour. Acad. Nat. Sci. Phila., 

 vol. I, p. 427, 



1841. Asellus vulgaris, Gould, Invert. Mass., p. 337. 



1905. Asellus communis, Richardson, Bull. U. S. Nat. Mus., 

 No. 54, p. 420. 



Body oblong-ovate, about three times as long as wide ; thorax 

 and abdomen of equal width. Head narrower in front than 

 behind and with anterior margin excavate. Eyes small, round, 

 compound, situated laterally half way between front and hind 

 margins. 



First antennae extending to the middle of last joint of second 

 pair; second joint longer than third which in turn is longer 

 than the first; flagellum made up of about fourteen joints. 

 Second antenna; more than half as long as body; fifth joint of 

 peduncle one and two-thirds as long as fourth joint which equals 

 the length of the first three joints together; flagellum much 

 longer than peduncle. 



