THE CRUSTACEA OF NEW JERSEY. 249 



lower face of metasome, and outer part cut off by transverse 

 suture, forming separate plate, inside which sometimes occurs 

 another much smaller plate. Incubatory pouch normal. 



Genera about 10, represented by some of the largest known 

 species. 



Key to the genera. 



a. Sides of head as seen dorsally entire, not produced laterally; eyes 

 lateral ; legs nearly all alike, sixth segment of propodus not or but little 

 expanded, and seventh segment prehensile. 

 h. Flagellum of second pair of antennae not multiarticulatc ; abdomen 

 a single segment. 

 c. Second pair of antennae much longer than first pair ; epimera dis- 

 tinct on all segments of thorax, including first ; maxillipeds with 

 palp of four articles ; no lateral sutures at base of abdomen. 



ERICHSONELLA. 



cc. Second pair of antennae shorter than first pair; epimera of all 



segments united with segments ; maxillipeds with palp of three 



articles ; lateral suture lines at base of abdomen. edotia. 



hb. Flagellum of second pair of antennae well developed, multiarticulatc ; 



abdomen (including terminal segment) of three segments with lateral 



sutures of another partly coalesced segment. idotea. 



aa. Sides of head emarginate or cleft and laterally produced beyond eyes ; 



eyes dorsal ; first three pairs of legs with sixth segment of propodus 



dilated and with reflexible dactylus forms a subchelate hand ; palp of 



maxillipeds of three segments. chiridotea. 



Genus ERICHSONELLA H. Richardson. 



Brichsonella (Benedict) Richardson, Amer. Nat., XXXIV, igoo, p. 228. 



Type Stenosoma Uliformis Say, second species. 

 Erichsonia (nee Westwood 1849) Dana, Amer. Journ. Sci. Art., (2) VIII, 



1849, p. 427. Type Stenosoma Uliformis Say, monotypic. 



Sides of head in dorsal view entire, not laterally produced. 

 Eyes lateral. Flagellum of second antennae formed of a single 

 clavate article. Second antennae much longer than first pair. 

 Maxillipeds with palp composed of four articles. Epimera of all 

 segments of thorax, including first, distinctly separated from seg- 

 ments. Abdomen formed of a single segment, and no lateral 

 sutures at its base. Legs nearly all alike, sixth article or pro- 

 podus not expanded, or but little expanded, and seventh article 

 prehensile. 



