578 BULLETIN 159, UNITED STATES NATIONAL MUSEUM 



138. Caudal rami as wide as long, their apical setae as long as uro- 



some; end segment of fifth legs three times as long as wide, 

 with 5 setae; littoral, among algae. -cf 9 Ameiropsis G. O. Sars, 1907 

 Caudal rami six to ten times as long as wide, their apical setae 

 as long as entire body; end segment, fifth legs, five to nine 

 times as long as wide; muddy bottom, shallow. 



cf 9 Stenocopia G. O. Sars, 1907 



139. End segment of second endopod with 1 inner, 2 apical setae, 



1 apical spine, much modified in male; basal expansion of 

 fifth leg large; littoral, among algae. 



cf 9 Amphiascus G. O. Sars, 1905 (p. 215) 

 End segment of second endopod with 3 inner and 3 apical setae, 

 no apical spine; basal expansion of fifth leg obsolete, end 

 segment elongate; pelagic, surface tow 9 Eremopus Brady, 1910 



140. Basal segment of first endopod triangular, half as wide as long; 



exopod natatory; fifth legs of medium size, end segment 



with 5 or 6 setae; among algae cf 9 Idomene Philippi, 1843 



Both rami of first legs prehensile, basal segment of endopod 



three to five times as long as wide 141 



141. Exopod of second antenna 3-segmented, 7 setae; inner seta of 



first endopod at center of basal segment; fifth legs with 



transverse chitin ribs; littoral, among algae. 



9 Dactylopusia Norman, 1903 (p. 206) 

 Exopod of second antenna 1-segmented, 4 setae; inner seta of 



first endopod at tip of basal segment; fifth legs without 



transverse chitin ribs; littoral, among algae 



cT 9 Diosaccus Boeck, 1872 (p. 213) 

 Exopod of second antenna 1-segmented, 3 setae; inner seta of 



first endopod at base of basal segment; fifth legs without 



transverse ribs; littoral, among a]gae__ 9 Dactylopusioides Brian, 1928 



142. Middle segments of second, third, and fourth endopods each 



with 2 setae 143 



Middle segments of second, third, and fourth endopods each 



with 1 seta 146 



Setae on middle segments of second, third, and fourth 



endopods not uniform 150 



143. Basal segment of first endopod shorter than 2 distal segments 



combined; metasome depressed; spines of first exopods 

 with tufted cilia; littoral and pelagic, d^ 9 Tisbe Lilljeborg, 1853 (p. 195) 

 Basal segment of first endopod longer than 2 distal segments 



combined; no tufted cilia on spines of first exopods 144 



144. Endopod of second legs 1-segmented, but longer than entire 



exopod, with 1 seta on each side near the base and 2 inside 



near the tip; among algae 9 Flavia Brady, 1899 



Endopod of second legs normal, 3-segmented 145 



145. Spines on end segments of first legs long, nearly straight, and 



fimbriated, the rami themselves neither widened nor flat- 

 tened; littoral, shallow 9 Idyanthe G. O. Sars, 1909 



Spines on end segments of first legs short, curved, and pulvil- 

 liform, the rami themselves considerably broadened and 

 flattened; littoral, among algae 9 Scutellidiiim Claus, 1866 



