432 piwceeihxc.s or the \ \tioxal museum. vol.38. 



A 56. Basal segmenl of inner ramus of firsl leg not larger than the resl of the ramus. 

 Body more or less depressed. Spines of outer rami of first legs with long 



cilia. Eye normal. Littoral and pelagic Idya. 



Basal eegmenl of inner ramus of first leg longer than the rest of the ramus. Inner 

 ramus of Becond leg modified in male. Eye present A 57. 



A 57. Rostrum very prominenl and very mobile. Body divisions sharply marked off 

 from one another. First antennae nine-segmented. Spines of outer rami of 

 aatatory legs coarsely denticulate. 6 to 20 fathoms, Laminaria and other 



algse Rhynckothalestri8. 



Rostrum not unusually prominent and mobile. Body divisions doI unusually 

 well marked. Body stout. First antennae five- to nine-segmented. Spinesof 

 outer rami of natatory legs commonly plain, not coarsely denticulate. Lit- 

 toral and tidal pools, among alga? Dactylopuswi. 



A 58. Middle segments of inner rami of natatory legs with one seta each. One e^g 



sac \ 59. 



Middle segments of inner rami of natatory legs not with one seta each, with 

 two on the second and third inner rami, or one on the third and fourth . .A 63. 



A 59. Basal segmenl of inner rami of first leg shorter than resl of ramus. Eye absent. 

 No rostrum. Body short, stout, and cylindrical. 20 to 30 fathoms, muddy 



bottom Parameira. 



Basal segment of inner rami of first leg longer than therest of the ramus. Inner 

 rami of second leg not modified in male. One egg sac A 60. 



A 60. Caudal rami long and narrow, ten to twenty times as long as wide. Rami of 

 natatory legs long and narrow. Bodyslender. Rostrum small. Eyeabsent. 

 Last two segments of inner rami of firsl legs, more or less benl on the first. 30 



to 50 fathoms, muddy bottom Stenocopia. 



Caudal rami not long and narrow, not more than one to five t Lines as long as wide. 

 Eye presenl A 61. 



A 61. Outer rami of second antenna' two-segmented. Rostrum small, but distinct. 

 Body slender. Firsl two segments of firsl antenna much the larger. Basal 

 segments of inner rami of first leg longer than the outer rami. Moderate 



depths anion-' alga? - imeiropsis. 



Outer rami of second antennas one-segmented. Body slender. Rostrum 



small A 62. 



A 62. Caudal rami scarcely Bpinulose. Anal opercle perfect!) smooth. Moderate 



depths anion- algae, rarely li Moral I"" ira. 



Caudal rami coarsely Bpinulose. Anal opercle denticulate. Segments of uro- 



Bome coarsely Bpinulose. Strictly littoral, brackish and tidal pools Vt'toi 



A 63. Middle segmenl of inner rami of Becond and third legs, with two Betas each, of 



fourth pair, one \ 64. 



Middle segmenl of inner rami of second legs with two seta-, of third and fourth 

 legs, one each. Inner rami of second leg£ modified in male. One egg sac. 



A 66. 



A 64. Terminal segmenl of fifth legs long and narrow, not foliaceous. Body short and 



depressed, its posterior part abruptly much narrowed. Male- not known. 



Rostrum small. < >neegg sac. Littoral, 10 to 10 fathoms Idyopsis. 



Terminal segmenl of fifth legs not long and narrow, foliaceous. Two egg sacs. 



Rostrum prominent. Inner rami of second legs modified in male \ 65. 



A 65. Outer rami of second antenna one-segmented. Bodj compressed in front, atten- 

 uate behind. The two segments of the fifth lege of male confluent. Littoral 



and tidal pools, among algae : Diosaccus. 



outer rami of second antenna two-segmented. Body slender, cylindrical. 

 The two segments of fifth legs of male uol confluent. Moderate depths among 

 algae; nol littoral Amphiascus. 



