No. 26.] ARTHROSTRACA OF CONNECTICUT. I93 



TANAIOIDEA OR CHELIFERA. 



Body nearly cylindrical ; head fused with first segment of 

 thorax, forming together a kind of carapace, which contains a 

 small branchial cavity on each side. Coxal plates inconspicuous. 

 Abdomen usually of six segments the last one of which is much 

 the longest. 



Second antennje smaller than first pair and originating directly 

 ventral to the latter. 



Mandibles with or without palp. First maxillae with a re- 

 flexed, setose palp. Second maxillse very small. Maxillipeds 

 coalesced at the base and each having an epignath projecting 

 within the branchial cavity. 



First pair of legs very strong, curving anteriorly, with cheli- 

 form propodus. Second pair sometimes unlike the succeeding 

 ones which are simple and ambulatory. 



Pleopods, when present, comparatively small and natatory, 

 with lamelliform rami. Uropods terminal, consisting of a short 

 peduncle and one or two terminal filaments. 



TANAID^. 



Body scarcely attenuated behind. First antennae without 

 accessory flagellum ; flagellum usually rudimentary in female, 

 multiarticulate in male. Second antennae with rudimentary 

 flagellum. 



Mandibles without palp. First maxillae with only a single 

 masticatory lobe. Second maxillae represented by minute rudi- 

 mentary lobes. Maxillipeds with narrow, falciform epignath. 



Second pair of legs not dift'ering essentially from the follow- 

 ing pairs. 



Pleopods with uniarticulate rami. Uropods simple or fur- 

 nished with two short filaments. 



Tanais cavolinii Milne-Edwards. 



1880. Tanais vittatus, Harger, Kept. U. S. Fish. Com. for 

 1878, p. 418, pi. 13, figs. 81, 82. 



1899. Tanais tomcntosus, G. O. Sars, Crust. Norway, vol. 

 2, p. 12, pi. 5. 



13 



