Ao. 2194. NORTH AMERICAN PARASITIC COPEPODS— WILSON. 57 



ming legs, then becoming filiform and chitinous, twisted and usually 

 flexed; trunk cylindrical and straight; abdomen straight, narrower 

 than trunk and of varying lengths; anal laminae minute and desti- 

 tute of setae; egg strings filiform and very long, eggs uniseriate and 

 strongly flattened. Two pairs of antennae, second pair chelate; 

 proboscis large and extensile; mandibles without teeth; one pair of 

 maxillae, no maxillipcds; four pairs of swimming legs close together 

 behind the head, first two pairs biramose, third and fourth pairs 

 uniramose. 



Internal generic characters of female. — Esophagus short, straight, 

 and inclined to the body axis; stomach without lateral lobes but with 

 one or two convolutions, passing insensibly into the intestine, which 

 is very narrow in the neck, but wider than the stomach in the trunk, 

 abruptly contracted at the posterior end of the abdomen into a nar- 

 now rectum; ovaries paired, short, wide, and strongly flattened be- 

 tween the intestine and the dorsal body wall at the anterior end of 

 the trunk; oviducts passing around the intestine to the ventral sur- 

 face and then straight back to the vulvae, eggs tightly packed like 

 a row of coins ; cement glands slender, cylindrical. 



Genus habitat. — This is a genus of muscle borers; they penetrate 

 from the outside surface of the host's body into the underlying tis- 

 sues, sometimes from the throat, sometimes from the sides of the 

 body, sometimes from the vicinity of the fins. In some species there 

 are peculiar frontal processes by means of which they fasten them- 

 selves to a bone, but they are usually anchored by the cephalic horns, 

 and a cyst is formed around the horns, the head, and the anterior 

 neck. 



Tyj)e of the genus, — Lemaeenicus radiatus Le Sueur, type by 

 elimination. 



{Lemaeenicus^ Lernaea^ and enico,, to torment or torture.) 



KET TO THE SPECIES OB" THE GEXDS LEUXAEEXICDS. 



1. 3 to 9 or 10 horns, cyUndrical, chitinous, branched 2 



1. Only 2 horns, a lateral pair, short and unbranched 3 



1. No horns, but instead 2 or 3 small and soft knobs 4 



2. Horns usually 5, arranged radially in one set; head in line with thorax; no 



attachment plates (40 mm.)* radiatus Le Sueur, 1S24, p. .'jQ. 



2. Horns in two sets, one at posterior end of head, tlie other behind the fourth 

 legs; head at right angles to thorax; four attachment plates in front of 

 antennae (12 mm.) poli/ccraus, new species, p. G2. 



2. Horns, 3^ triangular or conical, in one set; no attachment plates; head at 



right angles to thorax (13 mm.) cncrasicholi (Turton), 1S07. 



3. Horns pointed backward; no attachment plates in front of antennae; neck 



often monlliform {2r, mm.) sprattac (Sowerby), 1804. 



S. Horns pointed laterally; four attachment plates in front of antennae; neck 

 never monlliform (25 mm.) afflxus, new species, p. G4. 



* Average total length of species. 



