556 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ii8 



numerical setation as common in the genus (s=seta; sp= spine; 

 a = aesthete). 



tegment 



13 2s 



14 2s, a 



15 2s 



16 2s, a 



17 2s 



18 2s 



19 2s, a 



20 Is 



21 Is 



22 Is + Is 



23 Is + Is, a 



24 6s, a 



Aesthetes subequal to short setae of proximal segments but much 

 shorter than long setae of other segments; most setae of segments 7-20 

 very long, reaching end of succeeding 3 segments or beyond; those of 

 segments 17, 19, and 20 the longest; many segments with irregularly 

 placed hairs. 



Mandible blade (fig. 1/ ) with prominent, incompletely rounded gap 

 separating first denticle from others; second denticle single, with hyaline 

 cap; others with doubled or tripled points of which one carries a 

 hyaline cap. Antenna and other cephalic appendages as typical for 

 the genus. 



Legs 1-4 (figs. 2d-g) comparatively elongate (fig. la). Segmenta- 

 tion and setation as typical for the genus, all setae plumose (not 

 completely illustrated in figures). Basal segment 1 of all legs with 

 inner seta; basal segment 2 with slender outer seta on legs 3-4. Leg 

 1 : Exopod segment 3 only a little longer than exopod 1, with 3 spines 

 and 4 setae, apical spines with hyaline membranes, innermost spine 

 subequal to or a little shorter than segment, apical seta usually 

 reaching considerably beyond apical spine; endopod 1-segmented, 

 with 6 setae, the apical reaching to end of exopod 3 or beyond. 



Legs 2-4: Exopod segment 3 with 3 spines and 5 setae; endopods 

 2-segmented, second segment with 6 setae in legs 2-3 and 5 setae 

 in leg 4, all apical setae reaching beyond exopod 3. Exopod segment 

 3 of legs 2-3 shorter than exopod segments 1 + 2 (about 1:1.24; 

 range 1 : 1.21-1.31), that of leg 4 subequal to segments 1 + 2 (1 : 1.08) ; 

 inner apical spine of leg 2 a little shorter than or subequal to exopod 



Figure 1. — Eurytemora arctica, new species, female: a, habitus, lateral view, leg 5 omitted 

 (Lake 4), and variation of cephalic protuberance (Lake 8); b, habitus with apex of anten- 

 nule, dorsal view (Lake 4); c, detail of right metasomal wing, lateral view; d, detail of 

 metasomal wings and urosome, dorsal view; e, genital segment, ventral view, with detail 

 of operculum; /, mandible, apex of blade; g, antennule. 



