272 



BULLETIN 158, UNITED STATES NATIONAL MUSEUM 



Female. — ^Body stout and a little depressed ; cephalic segment the 

 same length as the rest of the metasome, rostrum short and not 

 well defined at its base. Urosome three-fourths as long as meta- 

 some; genital segment distinctly divided; caudal rami one-half 

 longer than wide, apical seta half the body length. First antennae 

 6-segmented, two basal segments enlarged, second segment with a 

 transverse row of setae across its dorsal surface; exopod of second 

 antenna minute and attached to the side of the basal endopod seg- 

 ment. First exopod 2-segmented, half as long as endopod, its end 

 segment twice the length of the basal segment with two apical 



geniculate setae and three outer 

 spines. End segment of fourth 

 exopod with three spines and 

 two setae. Basal expansion of 

 fifth legs strongly curved with 

 four setae, the second outer one 

 the longest. Distal segment 

 ovate, contracted at its base, 

 evenly rounded at its tip, with 

 five setae, the second inner one 

 the longest. Total length, 0.4- 

 0.5 mm. 



Male. — Smaller than the fe- 

 male and more slender; second 

 legs enlarged, the endopod 

 reaching beyond the tip of the 

 middle exopod segment, its end 

 segment five times as long as 

 wide, with two long apical setae 

 and a very short inner one ; third 

 and fourth exopods enlarged and 

 widened, especially the two basal 

 segments of the third exopod, the end segments armed with very long 

 and coarse spines. Third endopod 3-segmented, the spine on the 

 middle segment bent outward and then forward into an S-shape; 

 endopod of fourth legs tipped with three setae. Basal expansion of 

 fifth legs obsolete, distal segment very small, narrowed at its base, 

 with three setae, the inner one the longest; rudimentary sixth legs 

 present on the ventral surface of the genital segment. Total length, 

 0.35-0.4 mm. 



Remarks. — This species is the smallest of the genus and may be 

 recognized by the structure of the first and fifth legs in the female, 

 and of the third and fourth legs in the male. This is the first report 

 of the species outside of Christiania Fiord, where Sars found it. 



Figure 168. — Laophonte nana: a. Female, 

 dorsal ; h, female, first leg ; c, female, 

 fifth leg; d, male, fifth aud sixth legs 



