342 



CRUSTACEA 



1. Centropages Kioyer. Thorax of 5 segments; abdomen of male 



of 5, of female of 4 segments; first antennae with 24 segments; the 2 



branches of all 5 pairs of legs 3-jointed: 13 species; 



A marine. 



C. typicus Kr. (Fig. 534). Fifth thoracic segment 

 with 2 lateral projections; first abdominal segment of 

 female with 4 thorn-like bristles; length 2 mm.; color 

 reddish or bluish, translucent: coast of New England; 

 Europe. 



2. Temora Baird. Furca long and slender; lurcai 

 bristles short; thorax of 4 segments; abdomen of male of 

 5, of female of 3 segments; first antennae with 24 seg- 

 ments ; the 2 branches of the 5 pairs of legs 2 to 4-jointed : 

 5 species ;^ marine. 



T. longicornis (0. F. Miiller) 

 (Fig. 535). Length 1.5 mm.: 

 very common, especially in the 



Fig. 534 

 Centropages 



typicus — 



dorsal aspect 



of female 



(Wheeler). 



Woods Hole: 

 winter; Europe. 



3. Metridia Boeck. Thorax of 4 seg- 

 ments, abdomen of male with 3 segments; first 

 antennae with 23 segments; the 2 branches of 

 the first 4 pairs of legs S-jointed; of the fifth 

 pair 2 to 4-jointed in female and 5-jointed in 

 the male: 10 species; marine. 



M. lucens Boeck (M. hibernica Brady and 

 Robertson) (Fig. 536). Length 2.5 mm.: New 



Fig. 536 — Metridia lu- 

 cens (Wheeler). A, dor- 

 sal aspect of male; B, 

 fifth pair of legs of male ; 

 C. fifth pair of legs ol 

 female. 



England coast; Europe. 



4. LlMNOCALANUS 



G. 0. Sars. Thorax of 5 segments ; abdomen in 

 female with either 3 or 4 segments, in male 

 with 5; body slender; furca very long; first 

 antennae 25-jointed; all the legs biramose, both 

 branches 3-jointed, except the outer branch of 

 male, which may be 2-jointed: 3 species; in 

 fresh and salt water. 



L. macrurus G. 0. Sars. Right outer 

 branch of fifth foot in male indistinctly 3- 

 jointed with a hook-like process on second 

 segment; length 2 mm.; color hyaline: cosmo- 

 politan; often common in deep lakes; Europe. 

 5. EuRYTEMORA Giesbrecht. Thorax of 5 segments; abdomen of 

 male with 5, of female with 3 segments; first antennae about as long as 



Fig. 535 — Temora lon- 

 gicornis (Wheeler). A, 

 dorsal aspect of female ; 

 B, fifth pair of legs of fe- 

 male : C, fifth pair of legs 

 of male. 



