NO. 1573. PARASITIC COPEPODS— WILSON. 363 



ble in the base of the sinus; anal laminae large but armed with non- 

 plumose setae. 



Second maxillipeds tipped with stout claws; all the swimming legs 

 biramose; rami of first pair two-jointed; exopods of second and third 

 pairs three- join ted, endopods two-jointed, all with rudimentary plu- 

 mose setas; fourth pair transformed into imperfectly jointed lamellae, 

 destitute of setae. Egg-tubes very slender and several times the 

 length of the body. 



Male. — Carapace like that of the female but proportionally larger, 

 frontal plates more prominent. Lateral lobes of the second thorax 

 segment corresponding to the first pair of dorsal plates in the female; 

 no lobes on the third segment; a rudimentary pair on the fourth seg- 

 ment, which are closely appressed to the anterior margin of the genital 

 segment. The latter smaller than in the female, with one pair of legs 

 at or just in front of the posterior corners. Abdomen small and two- 

 jointed; anal laminae large and armed with plumose setae. Append- 

 ages as in the female. 



{Echthrogaleus, ^xOpog, an enemy, and yaXsog^ a shark.) 



KEY TO THE SPECIES. 



a. Females, tliird dorsal plates much enlarged, covering half the genital segment 

 or more; genital segment also enlarged, sometimes to the size of the carapace; 



abdomen small, one-jointed , hidden h. 



a. Males, no dorsal plates or only the rudiments of them; genital segment scarcely 



enlarged ; abdomen entirely free and two-jointed i. 



h. Body more than twice as long as wide; third dorsal plates with rounded 



anterior corners, without spines c. 



h. Body short and wide, length to width as 5 to 3; third dorsal plates with 



sharp spines at the anterior corners /. 



c. Carapace definitely wider than long; posterior lobes of genital segment paral- 

 lel and not touching along the mid-line d. 



c. Carapace as long as, or longer than, wide; posterior lolies of genital segment 



convergent and overlapping on the mid-line e. 



d. Carapace larger than the genital segment; fourth segment plates without 

 transparent dots and covering more than half the genital segment. 



braccatus Dana, 1852, p. 366. 



d. Carapace much smaller than the genital segment; fourth segment plates 



covered with transparent dots and overlapping less than half the genital 



segment coleoptratus Guerin, 1837, p. 367. 



e. Carapace definitely longer than wide; al:)domen small and entirely concealed, 

 not even the anal lamina; visible in dorsal view. 



affinis Milne Edwards, 1840, p. .364. 

 e. Carapace the same length and width; abdomen half as large as the genital seg- 

 ment and partly visible in dorsal view indistinctus Kroyer, 1863, p. 364. 



/. Posterior carapace lobes not touching the third dorsal plates; genital seg- 

 ment decidedly smaller than the carapace g. 



f. Posterior lobes of the carapace overlapping the third dorsal plates; genital 



segment as large as or larger than the carapace h. 



g. Third dorsal plates covering more than half the genital segment and toothed on 

 their posterior and inner margins; fifth legs projecting beyond the lobes of the 

 genital segment; abdomen invisible denticulatus Smith, 1874, p. 369. 



