NO. 1573. PARASITIC COPEPODS— WILSON. 457 



NESIPPUS ORIENTALIS iNogaus male) Heller. 



Nesippus orientalis Heller, 1865, p. 194, jil. xviii, figs. 2, 3. 



After establishing his new genus Nesippus in 1865, Heller describes 

 two species, orientalis and crypturus. 



For the first of these, which would become the type of the new 

 genus, he presents the female and a form which he claims to be the 

 male, and gives admirable descriptions and figures of each. 



But the "male" difl'ers from the female only in being smaller, in 

 having a sharp terminal claw on the second maxillipeds, longer 

 plumose setae on the swimming legs, and in the abdomen being 

 visible in dorsal view. If the figure of the young female of the 

 species alatus given in the present paper (Plate XXXIV, fig. 205) be 

 compared with that of the adidt female (fig. 194), exactly the same 

 differences will be fomid, wliile the true male (fig. 206) has a very dif- 

 ferent carapace, and the second and third thorax segments are free in- 

 stead of being fused as in the young female (see p. 429). This "male" 

 of Heller's therefore was almost certainly a yoiing female similar to 

 those repeatedly found by the present author in company with the 

 adults of alatus. 



CALIGUS PARADOXUS (Nogaus male) Otto, 

 Caligus paradoxus Otto, 1828, p. 352, pi. xxir, ligs. 5, 6. 

 The male of Demoleus paradoxus (see p. 349). 



ECHTHROGALEUS PERSPICAX (Nogaus male) Olsson. 



Echthrogaleus perspicax Olsson, 1869, p. 18, pi. i, figs. 6, 7. 



The description and figures of this species are found to correspond 

 in every particular with those of the other males of the genus, and 

 the species will therefore stand as originally described. 



NOGAGUS PRODUCTUS Gerstaecker- 



Nogagus productus Gerstaecker, 1853, p. 63, pi. iv, figs. 1-10. 



This proves to be a female Dinematura, Gerstaecker wrongly sub- 

 stituting the name Nogagus on the ground of priority (see p. 441). 



NOGAGUS SOCIALIS Olsson, 



Nogagus socialis Olsson, 1869, p. 16, pi. i, fig. 5. 



Found on the body of Acanthias vulgaris in the Sea of Skagerrack, 

 together with both sexes of Echthrogaleus perspicax. 



From the excellent description and figures given by Olsson we find 

 that the carapace is elliptical with narrow posterior lobes ; the genital 

 segment is not enlarged; one pair of legs are visible at its posterior 

 corners; the abdomen is one-jointed, with small anal lanfinge; the 



