AMPHIPOD GENUS PARATHEMISTO BOWMAN 345 



placed it in Euthemisto, while the female had to be referred to Para- 

 themisto. In combining the two genera, Stephensen returned to the 

 oldest generic name, apparently not realizing that it had been pre- 

 occupied. K. H. Barnard (1930) pointed out that Themisto was not 

 available and that Bocck's name had to be used. In spite of this, 

 some authors continue to refer to the genus as Themisto. 



K. H. Barnard (1930) retains Parathemisto and Euthemisto as sub- 

 genera of Parathemisto, a course which is followed by Hurley (1955) 

 and Vinogradov (1956). I believe this is the most satisfactory way 

 to deal with this group of amphipods. Although the differences 

 between Euthemisto and Parathemisto are sufficiently clear cut so that 

 there is no difficulty in assigning all the known species to one or the 

 other, they are not as great as those which separate the other genera 

 of the family Hyperiidae. 



Keys to species of Parathemisto have been given by Barnard (1930, 

 p. 420), Stephensen (1923, p. 19, European species), and Hurley 

 (1955, New Zealand species). 



Subgenus Parathemisto Boeck 



Dorsal spines absent. Flagcllum of female antenna 1 slender, 

 straight. Carpus of P3-4 only slightly expanded. P5-7 subequal 

 in length. Peduncle of uropod 3 strongly produced at inner distal 

 angle. Inner ramus of uropod 3 serrate on medial and lateral mar- 

 gins. Type species, by subsequent designation, Parathemisto abys- 

 sorum Boeck. 



Key to the Species of the Subgenus Parathemisto 



1. In length P5>P7>P6; dactyls not pectinate. Posterior margin of PI pro- 



podus bearing several long setae. Maxilliped without a distal row of setae 



on basal plate abyssorum Boeck 



In length P6>P7>P5; dactyls of P5-6 pectinate at base. Posterior margin 

 of PI propodus serrate but without setae on distal margin. Maxilliped 

 with distal row of long setae on basal plate 2 



2. Antennae 1 and 2 of female subequal. Length of adult 4.5-8.5 mm. 



pacifica Stebbing 

 Antenna 2 longer than antenna 1. Length of adult 9-17 mm. 



japonica Bovallius 



Parathemisto (Parathemisto) pacifica Stebbing 



Figures 1; 2,a,j-k; 3,a-e; 4-10 



Parathemisto pacifica Stebbing, 1888, pp, 1420-1423 [no figures]. — Bovallius, 



1889, p. 263. 

 Parathemisto oblivia (Kr0yer), Holmes, 1904, p. 233. 

 Themisto abyssorutn (Boeck), Shoemaker, 1930, pp. 132-133 [specimens from 



Nanaimo, British Columbia only].— Wailes, 1929, p. 5. 



