390 BULLETIN" 15 8, UNITED STATES NATIONAL MUSEUM 



Color. — Body opaque and brownish white; digestive tract reddish 

 yellow; ova dark green; eye ruby red. 



Female. — Body strongly compressed, highly arched dorsally; 

 fourth and fifth segments raised but little above the third segment, 

 but carried backward far behind the genital segment. Sometimes 

 the posterior end is turned downward and forward pushing the 

 urosome forward until its tip falls beneath the head. Urosome only 

 a third or a fourth as long as the metasome, and usually turned 

 down at right angles to the latter. First antennae 10-segmented, 

 the second segment enlarged and densely setose, the last four seg- 

 ments turned forward; second antenna cylindrical, its second seg- 

 ment twice as long as wide. Basal segment of fifth leg wider and 

 three-fourths as long as the terminal segment, without a seta on 

 its inner margin. Terminal segment three times as long as wide. 



FiGUKH 239. — Doropygus pulex: a. Female, lateral (after Tho- 

 rell) ; b, male, lateral; c, male, fifth leg; d, female, fifth leg 



with four small spines on the outer margin near the distal end ; the 

 tip is rounded, without the long filiform seta at the outer corner 

 and the short spine inside of it. Total length, 3-4 mm. 



Male. — Body slender, the body axis nearly straight and not curved 

 ventrally; first and fifth segments very short; second segment twice 

 the length of the first; third and fourth segments twice the length 

 of the second. Urosome 5-segmented, the first and second abdominal 

 segments the same length, each longer than the genital segment and 

 also longer than either of the last two segments. Anal segment 

 very short ; caudal rami rather stout, as long as the last two segments 

 combined, each with two minute apical spines. Total length, 

 1.45-1.6 mm. 



Remarks. — This species has been found in several different hosts. 

 It seems to develop a larger size in the Mediterranean than in the 

 colder oceans. The fact that the urosome is always turned at least 

 at right angles to the metasome, and sometimes even inclined for- 

 w^ard, is sufficient to distinguish this from the preceding species. 



