32 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 53. 



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when it is immature but after it has acquired its yolk material and 

 become fully ripe, just before it passes out into the external sack. 



SYSTEMATIC TREATMENT. 



Family LERNAEIDAE. 



Family characters of female. — The largest of the parasitic cope- 

 pods, sometimes reaching a length of 200 to 250 mm., exclusive of 

 the egg strings. Body more or less cylindrical, elongate, and unseg- 

 mented; separable into three regions — a ccphalothorax furnished 

 with horns or processes, a free thorax in the form of a narrow cylin- 

 drical neck, and a trunk comprising the rest of the body, more or less 

 swollen and either straight or sigmoid; anal laminae present but 

 often minute; egg strings paired, either short club-shaped sacks or 

 long threads, straight, coiled into loose masses, or twisted into regu- 

 lar spirals. Antennae distinctly dorsal, second pair chelate; mouth 

 in the form of a sucking tube, more or less protrusible; a tripartite 

 eye buried in the tissues above the esophagus; mandibles and two 

 pairs of maxillae, but no maxillipeds except in Lernaea; three, four, 

 or five pairs of swimming legs; at least the first two pairs biramose, 

 rami two or three jointed, the others uniramose with jointed rami. 



Adult female with the head and part of the neck buried in the 

 tissues of the host and firmly anchored in such a way as to bring the 

 mouth in contact with some copious blood supply. 



Family characters of male. — Not developed beyond the fourth 

 copepodid stage, at which time it becomes sexually mature. Body 

 like that of Cyclops^ comprising a cephalcthorax covered dorsally 

 with a carapace, a free thorax, a genital segment, and a jointed abdo- 

 men armed with a pair of large anal laminae; antennae and mouth 

 parts like those of the female; proboscis also more or less protrusible; 

 sometimes a sixth pair of rudimentary legs on the genital segment; 

 a pair of large prehen.sile maxillipeds a little distance behind the 

 mouth tube. 



The male never bores into the tissues of its host nor becomes perma- 

 nently anchored in any way, nor is it ever found attached to or in 

 company with the adult female. 



KEY TO THE SUBFAMILIES AND CEXEKA. 



1. Trunk straight; swimming legs widely separated, the posterior pair close to 

 the vulvae; egg cases sacl<like; eggs uuiltiseriate Lcnmcinac 2 



1. Trunk straight; first two pairs of swiniuiing legs close together and near the 

 Lead, the others at short intervals; egg cases filiform and straight or 

 coiled into regular spirals; eggs uniserlate Lcniaccnicinnc 3 



1. Trunk with sigmoid curve; all the swinnning legs close together and near 

 the head; egg cases filiform and convolute or coiled into spirals; eggs uni- 

 serlate and very numerous Lcniucoccrinac 8 



