348 



CRUSTACEA 



to lO-jointed, in tlie male modified and prehensile; second antennae usnally 



biiamose; fifth pair of feet 1 or 2-jointed and serving as egg support in 



the female; heart absent; usually a single egg sac present: about 30 



genera and ^')0 species, mostly marine, usually found among vegetation. 



Key to the genera of Harpacticidae here described : 



fli Fresh-wator animals 1. Canthocamptus 



O2 Marine animals. 



61 The outer branch of the first pair of legs much longer than the inner. 



2. Harpacticus 



62 The inner branch longer than the outer 3. Ectinosoma 



1. Canthocamptus Westwood (Fig. 549). Thorax of 4 segments; 

 head with a rostrum ; first antennae with 6 to 9 joints, usually 8 in the 

 female; abdomen 5-jointed in the male and 4 in the 

 female: mostly in fresh water; about 6 American species. 



C. minutus Claus. Body 1 mm. long; first antennae 

 8-jointed; legs 3-jointed in both branches, except the 

 fifth leg, which is 2-jointed: eastern and central states; 

 common, especially in muddy pools; Europe. 



2. Harpacticus Milne-Edwards. Outer branch of 

 the first leg 3-jointed, almost twice as long as the 2-jointed 

 inner branch; conical rostrum present; third pair of legs 

 with very strong outer branch: 12 species; marine. 



H. chelifer (0. F. Miiller). Length of male 1 mm.; 

 first pair of legs with 1 spine, outer branch with 3; inner 

 caudal spines longer than the cephalothorax ; Atlantic 



caTXs ^«^^t' E^^^P^- 



F.H^ur) ^' Ectinosoma Boeck. First antennae 5 to 7-jointed; 



first pair of legs scarcely smaller than the others and with 

 the inner branch longer than the outer; fifth pair of legs 2-jointed: 12 

 species. 



E. curticorne Boeck. Length .7 mm.; color dark brown; first an- 

 tennae very short, 6-jointed: common in Narragansett Bay; Europe. 



4. Parategastes G. 0. Sars. First antennae 6 or 7-jointed; second 

 antennae with a 1-jointed outer branch; last pair of legs very large in 

 the female, with an expansion on the basal joint. 



P. sphaericus Claus. Length .35 mm.; color brown: abundant in 

 Narragansett Bay; Europe. 



Family 6. ERGASILIDAE.* 



Body more or less cylindrical, somewhat like Cyclops in shape, 

 usually well segmented ; first pair of antennae 5 to 7-jointed, second 3 or 



* '-North American Parasitic Copepods Belonging to the Family Ergasilidae," by 

 C. B. Wilson, Proc. U. S. Nat. Mus., Vol. 39, p. 263, 1911. 



