376 



BULLETIN" 15 8, UNITED STATES NATIONAL MUSEUM 



KEY TO THE SPECIES (FEMALES) 



1. Exopod of fourth leg 3-segmentecl ; second antenna without 



Sleeves, claw not toothed 2 



Exopod of fourth leg 2-segmented ; second antenna with large 



sleeves inclosing bases of second and third segments manicatus (p. 376) 



Exopod of fourth leg 1-segmented ; terminal claw of second an- 

 tenna with several small teeth near base of inner margin, labracis (p. 377) 



2. Basal segment of second antenna with convex outer margin, 



much wider than second segment ; apical claw with smooth 



inner margin ^" centrarchldarum p. 377) 



Basal segment of second antenna with straight outer margin, 

 much narrower and shorter than second segment ; apical claw 

 with large inner tooth funduli (p. 378) 



ERGASILUS MANICATUS Wilson 



FlGUKE 230 



Ergasilus manicatus Wilson, Proc. U. S. Nat. Mus., vol. 39, p. 337, pi. 44, 1911. 



Occurrence. — Females found abundantly on the gills of the silver- 

 sides minnow {Menidia notata) and the 2-spined stickleback {Gas- 

 terosteus hispinosus) , everywhere within the present area. 

 Dist7'{butio7i. — Not reported outside of the Woods Hole area. 



Color. — The adult females are 

 a uniform milky white, the only 

 spot of pigment being the eye, 

 which is ruby-red; eggs also 

 white until almost ready to 

 hatch. 



Female. — Head fused with 

 first segment, the two a little 

 longer than wide, the antennal 

 area projecting from the center 

 of the anterior margin ; urosome 

 one-fourth as long as metasome ; 

 genital segment barrel-shaped; 

 caudal rami wider than long. 

 Each of the first two segments of the second antennae prolonged into 

 a rounded puff sleeve, enclosing the base of the next segment; ter- 

 minal segment a stout claw with a blunt tooth on the inner margin 

 near the base ; fifth legs each a tiny knob tipped with one seta. Total 

 length, 0.65-0.85 mm. 

 Male. — Unknown. 



Remarks. — This species was first discovered by Rathbun, who 

 made a series of drawings showing its distinctive characters; these 

 were turned over to the present author and published in the reference 

 given above. 



Figure 230. — Ergasilus manicatws: a, 

 male, dorsal ; b, female, fourth leg 



Fe- 



