374 0. Harger Isopodafrom New England. 



Chiridotea* gen. nov. 



First three pairs of legs terminated by prehensile hands, in 

 each of which the carpus is short and triangular, the propodus 

 is robust and the dactylus capable of complete flexion on the 

 propodus. Antennas with an articulated flagellum. Head 

 dilated laterally. Operculum vaulted, with two apical plates. 



This genus is founded on Ch. caeca (Idotea cceca Say), which 

 occurs on this coast from Florida to Halifax, Nova Scotia. 

 It includes Ch. Tuftsii (Idotea Tuftsii Stimpson), of the New 

 England coast from Long Island Sound to the Bay of Fundy, 

 and, as constituted above, would also include Ch. entomon 

 (Idotea en tomon Bosc.), from the Baltic and other European local- 

 ities, and Ch. Sdbini (Idothea Sabini Krdyer), from the Arctic. 

 The above mentioned species ought certainly to be separated 

 from Idotea tricuspidata Desm., which may properly be regarded 

 as the type of the genus Idotea Fabr. 



Synidotea,-\ gen. nov. 



Antennae with an articulated flagellum. Epimeral sutures 

 not evident above. Pleon apparently composed of two seg- 

 ments, united above but separated at the sides by short incis- 

 ions. Operculum with a single apical plate. Palpus of maxil- 

 lipeds three-jointed. 



This genus is founded on S. nodulosa (Idothea nodulosa Kroyer), 

 who appears to have been misled, in his unnatural description 

 of the epimera, by the marginal thickening of the segments. 

 He describes the epimera as evident even on the first segment. 



Astacilla Americana, sp. nov. 



Body nearly uniform in size throughout in the female, with 

 the fourth thoracic segment narrow in the male, tuberculated. 

 Head united with the first thoracic segment, and, together with 

 it, twice the length of the next two segments ; excavated in 



I ^D * ' 



front, with the sides extending beyond the middle of first anten- 

 nular segment, tuberculated above, crossed between and behind 

 the eyes by two transverse grooves, while a third groove indi- 

 cates the suture of the first thoracic segment. Eyes lateral, 

 round-ovate, broadest in front. Antennulae four-jointed, 

 slightly surpassing the second segment of the antennae in the 

 female, nearly attaining the middle of the third in the male; 

 basal segment swollen, nearly as long as the next two which 

 are much more slender, last or flagellar segment shorter than 

 the peduncle in the female, longer than the peduncle in the 

 male. Antennae about three -fourths as long as the body, 

 fourth segment longest, then the fifth and third; first two seg- 

 ments short; flagellum three-jointed, short. First thoracic 



* From x?'P- a hand, and Idotea. f From ah', with or together, and Idotea. 



