NO. 1573. . PARASITIC COPEPODS— WILSON. 425 



Appendages like those of the female ; second maxillipeds much swollen, 

 with forceps knobs or a flattened terminal claw. All the legs bira- 

 mose, rami like those of the female. 

 (Nesippus, etymology unknown.) 



KEY TO THE SPECIES. 



a. Females, carapace much wider than long; second and third thorax segments 

 fused inter se; fourth segment with small dorsal plates; genital segment longer 



than the carapace; abdomen hidden - - - ''• 



a. Males, carapace as long as wide; second and third thorax segments distinct; 

 fourth segment without dorsal plates; genital segment mucli smaller than cara- 

 pace; abdomen wholly visible (f- 



h. Fourth segment plates not reaching the genital segment; lateral lobes of 



the fused second and third segments narrow and well rounded c. 



h. Fourth segment plates overlapping the genital segment a little; lateral 

 lobes on the fused second and third segments large, wid(\ and angular. 



alatus Wilson, 1905, p. 420. 

 c. Genital segment medium size, quadrangular, with rounded corners and no 

 posterior lobes; abdomen largely visible from aljove. 



angustatus Beneden, 1892, p. 431. 

 c. Genital segment somewhat enlarged, elliptical, with long and broad posterior 

 lol)es, separated by a narrow median sinus; abdomen wholly concealed. 



cryphirus Heller, 1805. 

 c. Genital segment much enlarged, ovate, with an evenly curved margin; no 



posterior lobes; abdomen entirely concealed orimtalis Heller, 1805. 



(1. Carapace wider than long; genital segment also wider than long, barrel- 

 shaped '■ 



(•/. Carapace and genital segment decidedly longer than wide; genital seg- 

 ment oblong with parallel sides J- 



e. Carapace without conspicilla, posterior lobes short; fourth segment with 

 strongly protruding sides; genital segment without rudirnentary legs. 



alatus Wilson, 1905, p. 420. 



(\ Conspicilla present; posterior carapace lobes narrow and elongate; sides of 



fourth segment protruding but little; fifth legs showing on sides of genital 



segment cvrticaudis Dana, 1852, p. 434. 



/. Less than 6 mm. in length; genital segment nearly as wide as long; fourth 

 segment biscuit-shaped, twice as wide as long. 



angustatus Beneden, 1892, p. 431. 

 /. From 8 to 11 mm. in length; fourth segment spindle-shaped, as long as 

 wide; genital segment one-third or one-half longer than wide. 



borealis Steenstrup and Fiitken. 1801, p. 437. 



This genus wasfoimded by Heller in 1865 upon two species obtained 

 on the Novara expedition at the island of Java. 



They were both obtained from the gills of sharks, and although 

 Heller does not make the statement, it is probable that they were 

 found in the shark's tlu'oat rather than in the gill cavity. 



Of one species which he called orientalis Heller claimed to have 

 both sexes, but a careful study of the figures and description of his 

 "male" show it to be really a young female before the egg strings 

 have developed. It is not a Nogaus form at all, but exactly like the 

 adult except that the genital segment is smaller and the abdomen not 



