574 BULLETIN 159, UNITED STATES NATIONAL MUSEUM 



113. Rami of first legs narrow cylindrical; middle segment of first 



exopod but little longer than wide; urosome fully as wide as 



metasome; moderate depths cT 9 Schizopera G. O. Sars, 1905 



Rami of first legs broadened into laminae; middle segment of 

 first exopod little longer than wide; metasome twice as 

 wide as urosome; moderate depths, among algae. 



& 9 Dactylopodella G. 0. Sars, 1906 



Rami of first legs of normal width; middle segment of first 

 exopod much longer than wide; second endopod always 

 3-segmented 114 



114. Middle segment of first exopod twice as long as wide; meta- 



some much wider than urosome; end segment of fifth legs 

 ovate, with 6 setules; washed from dredgings. 



? Eudactylopus A. Scott, 1909 

 Middle segment of first exopod four to six times as long as 

 wide; urosome nearly as wide as metasome; end segment of 

 fifth legs tetragonal, 8 setae; littoral, among algae. 



d^ ? Microthalestris G. O. Sars, 1905 (p. 204) 



115. Stout anterior spines on second segment of first antenna; 1 or 



2 apical caudal setae enlarged at base; fourth legs tipped 



with setae only; littoral, among algae. _ cf 9 Bradyellopsis Brian, 1924 



No spines on second segment of first antennae; outer caudal 

 setae transformed into acuminate stylets; fourth leg with a 

 stylet and a seta; beach sands cf 9 Goffinella, new genus (p. 260) 



No spines on first antennae; caudal setae not enlarged or 

 modified 116 



116. Endopods of second and third legs 2-segmented, of fourth legs 



3-segmented; forehead without lenses; sandy bottom, 



shallow water cf 9 Leptomesochra G. O. Sars, 1911 



Endopods of second legs 2-segmented, of third and fourth legs 

 3-segmented; forehead with 2 conspicuous lenses; pelagic, 

 at surface cf 9 Miracia Dana, 1846 (p. 284) 



Endopods of second, third, and fourth legs 3-segmented 117 



117. Exopods fringed with stout spinules; apical setae exceptionally 



long; rami of first legs subequal; fifth legs large, with stout 



setae; littoral, among algae cf 9 Psyllocamptus T. Scott, 1899 



Exopods fringed with hairs, no spinules; apical setae of nor- 

 mal length; rami of first legs unequal 118 



118. First antenna 4-segmented; fifth legs diminutive, with weak 



setae; rows of small spinules across ventral surface of the 



abdominal segments; littoral cf Sigmatidium Giesbrecht, 1881 



First antenna 8-segmented; fifth legs large and broad, with 

 enlarged setae; no spinules across ventral surface of ab- 

 dominal segments; pelagic, surface tow. 9 Tydemanella A. Scott, 1909 



First antennae 9-segmented; fifth legs very large and broad, 

 with minute setae; second endopod 2-segmented in male; 

 no ventral spinules on the abdomen; muddy bottoms. 



cf 9 Plesiothalestris Brian, 1928 



