660 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvni. 



legs are attached to its posterior lateral margins, which are much 

 widened through their bases. The genital segment is oblong, with 

 well-rounded anterior corners where it is contracted into a neck on 

 joining the free segment. It carries two pairs of papillae, one at the 

 posterior corners and the other on the lateral margins just in front of 

 those corners. 



The abdomen is small, only half the length of the genital segment, 

 as wide as long, with no trace of segmentation. The anal laminae are 

 much larger than in the female and their setae are very much longer 

 and stouter. 



The second antennae are enlarged as usual in this sex into clasping 

 organs, but the branches are reduced to mere knobs. The rami of the 

 third legs are especially prominent and protrude a long distance from 

 the margin of the basal apron. 



The fourth legs are relatively much larger than in the female; the 

 basal joints alone reach more than three-quarters of the length of the 

 genital segment, while the tips extend well beyond the ends of the 

 anal laminae. 



Total length 3.3 mm; length of carapace 2.2 mm.; width of same 

 2.2 mm.; length of genital segment 0.58 mm.; length of abdomen 

 0.3 mm. 



Color somewhat darker than in the female. 



The National Museum collection includes three lots of this new 

 species, all of which were obtained at Lota, Chile, during the voyage 

 of the United States Bureau of Fisheries steamer Albatross in 1887-88. 



The first two lots are numbered 1502 and 1503, while the third lot 

 is unnumbered. No host is given for the first lot; the second, 1503, 

 was taken from a ray, while the third was taken from a species of 

 Sebastes. This third lot includes twent} r -five females and two males, 

 which are excellently preserved. 



The species resembles parviventris at first sight, but is considerably 

 smaller and the proportions of the various body regions are markedly 

 different. This is seen especially in the general shape of the carapace 

 and genital segment and in the relative size of the two. 



The abdomen, also, in this species is relatively longer and is made 

 up of two segments, while in parviventris it is shorter and undivided. 

 The egg strings in parviventris are as long as the entire bod} 7 , while 

 here they are only three-fifths as long. In parviventris the furca has 

 a broad U shape, the branches widely separate and parallel; here the 

 furca is much smaller, V shaped, with the branches starting close 

 together and diverging rapidly. In this species, also, the second 

 maxillipeds are small and weak, while the fourth legs are very large 

 and strong; in parviventris exactly the opposite is true. 



