590 BULLETIN 159, UNITED STATES NATIONAL MUSEUM 



61. Setae of fifth leg short and unequal; second antenna half as long 



as first, its end segment with 2 unequal apical claws and no 



setae; parasitic on echinoderms 9 Astericola Rosoll, 1888 



Setae of fifth leg long and equal; second antenna one-fourth as 

 long as first, its end segment with 6 long apical setae, 2 of 

 them geniculate; pelagic, at surface. 



cf 9 Oithonina G. O. Sars, 1913 (p. 316) 



62. Second antennae prehensile, with 1 or more apical claws 63 



Second antennae nonprehensile, with setae only, no claws 67 



63. Second antenna much shorter than first pair, with 1 apical claw 64 



Second antenna much shorter than first pair, with 2 apical 



claws; fifth leg with 4 equal spines; first antenna elongate and 



6-segmented; pelagic, moderate depths. 



9 Pseudolubbockia G. O. Sars, 1909 

 Second antenna much shorter than first pair, with 4 or more 



apical claws 65 



Second antenna three or four times as long as first pair 66 



64. Head produced on each side in female, not in the male; first 



antenna 7-segmented, sparsely setose; fifth leg with 3 filiform 



setae; pallial cavity of moUusk cf 9 Conchocheres G. O. Sars, 1918 



Head smooth in female; a maxillary hook behind each second 

 antenna; first antenna 8- to 10-segmented; fifth leg with 

 numerous filiform setae; gills of fishes 9 Haemaphilus Hesse, 1871 



65. Apical claws of second antenna equal and jointed at the center; 



fifth leg narrow oblong, with 3 spines and 1 filiform seta; 



pelagic, 100 fathoms cf 9 Pseudomolgus G. O. Sars, 1916 



Apical claws of second antenna very unequal and not jointed; 

 fifth leg a short and wide lamina with 3 setae and no spines; 

 in an ascidian 9 Lichomolgidium Kossmann, 1877 



66. Head produced laterally on each side; first and second meta- 



some segments fused, half as wide as head; legs visible in 



dorsal view; gills of fishes 9 Macrobrachinus Hesse, 1871 



Head not produced laterally; first 2 metasome segments sepa- 

 rated and nearly as wide as head; legs not visible in dorsal 

 view; gills of fishes 9 Megabrachinus Hesse, 1871 



67. Head and 5 metasome segments separated; urosome 4-seg- 



mented; caudal rami short and wide, each with 4 apical and 1 



lateral setae; marine, littoral cf 9 Oncaea Philippi, 1843 (p. 350) 



First 2 metasome segments fused with the head; urosome 2- 

 segmented; caudal rami long and narrow, each with 1 apical 

 seta; gills of fishes 9 Metoponanaphrissontes Hesse, 1871 



68. Body cylindrical, metasome the same diameter throughout; 



fifth leg with 3 apical setae; first antennae slender, 6-seg- 

 mented; parasitic on annelids 9 Bhodinicola Levinsen, 1878 



Body cyclopoid, metasome widened anteriorly and narrowed 



posteriorly, and more or less depressed 69 



69. Second antenna nonprehensile, with 6 unequal apical setae; 



end segment of fifth leg triangular, with 4 subequal apical 



setae; brackish water cf 9 Halicyclops Norman, 1903 (p. 320) 



Second antenna prehensile, with apical claws but no setae 70 



