112 U.S. NATIONAL MUSEUM BULLETIN 23 6 



nules. S. purpurocincta seems to be a characteristically colored 

 species, a peculiarity I could not compare with my specimen, which 

 is totally colorless from storage in alcohol. My specimen also differs 

 from S. arthuri (as described by Monk, 1941, p, 97) by the greater 

 length of the 2nd endopodal segment of leg 2. As, S. purpurocincta 

 is not completely described by its author (only the antennules and 

 none of the remaining appendages are figured), I have thought it 

 advisable to describe my specimen as completely as possible and to 

 introduce a new trivial name, referring to the spinulosity of the legs. 

 As stated above, the complex S. arthuri, S. arthuri var. magnum, S. 

 purporocincta, and S. dentipes need closer investigation. 



A single specimen of this new form was washed from caulerpas 

 off the reef ridge north of Falarik in the Ifaluk Atoll. 



Scutellidiuni ligusticum (Brian, 1920) 



Figures 37-39 



Idya ligustica Brian, 1920, p. 30, figs. 1-6; 1921, p. 73, pi. 9 (figs. 5-8); 1923a, 



p. 177. 

 Idyaea ligustica. — Brian, 1923, p. 129. 



Tisbe ligustica.— Gmney, 1927, p. 496.— Willey, 1930, p. 84. 

 Machairopus ligusticus. — Brian, 1928, pp. 1, 36; 1928a, pp. 298, 311. — Vatova, 



1928, p. 181.— Lang, 1936, p. 37. 

 ScutelUdium ligusticum. — Lang, 1948, p. 395, fig. 172 (no. 3). — Noodt, 1955a, 



p. 202, fig. 1. 

 Psamathe machairopoides Monard, 1928, p. 331, figs. 13 (no. 5), 14 (no. 1).— Lang, 



1934, p. 20.— Monard, 1935a, p. 80. 

 Machairopus machairopoides. — Lang, 1936, p. 37. 

 ScutelUdium machairopoides. — Sewell, 1940, pp. 164, 169, 356, 366, 368, 371, 



figs. 15, 16. 



Material. — Loc. 431, 1 ad. cf, 0.38 mm. Loc. 588, 1 ad. cf, 

 0.36 mm. Loc. 589, 1 9 cop. stage V, 0.41 mm.; 5 ad. 99, 0.38-0.42 

 mm. (0.39 mm.); 6 ad. d'cf, 0.33-0.37 mm. (0.35 mm.). Loc. 590, 

 1 ad. 9, 0.38 mm. Loc. 591, 1 ad. 9, 0.36 mm. Loc. 638, 1 ad. 

 d', 0.32 mm. 



Description. — The following is based on the female specimen from 

 locality 591 and the male specimen from locality 588. Both speci- 

 mens, after having been figured, were dissected and mounted. 



Adult female, total length 0.36 mm.; greatest diameter 0.17 mm. 



Body compressed dorsoventrally, ovoid in dorsal view, not partic- 

 ularly broad, greatest width at end of cephalic somite, with fairly 

 distinct division in cephalo thorax and abdomen (fig. 37a). Head 

 and 1st thoracic somite completely fused to form cephalic somite; in 

 dorsal aspect narrowly rounded anteriorly, rostrum invisible from 

 above; distal border cut off squarely. In lateral aspect back almost 

 straight, curving broadly at anterior end to form small, bluntly 

 pointed rostrum, completely hidden between basal parts of anten- 



