150 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



antennule; fig. 21). Some of the setae of apical segments modified 

 by division into one or more joints (fig. 21). Aesthetes present on 

 most of the segments, stouter than the setae and of uniform width 

 throughout their length; those of the proximal segments (fig. 16) 

 stouter than those beyond the midportion of the antennule; the 

 longest that on segment 10 (reaching to the middle of segment 15). 

 Segments 13-22 and 24-25 with small groups of surface spinules 

 (figs. 15 and 21). Summary of setation of individual segments as 

 follows (s=seta; a=aesthete): 



Antenna (fig. 20) with basipod of two weU-defined segments, the 

 proximal with a plumose inner seta, the distal with two unarmed setae. 

 Exopod reaching beyond inner ramus by about half the length of its 

 apical segment; 8-segmented, the fu'st seven segments differing little 

 in length from one another, but progressively narrowed from the basal 

 segment, each with a single inner seta; apical segment about 3 times 

 the length of the other segments and with four terminally placed setae. 

 Endopod of two stoutly developed segments, the apical (measured to 

 end of outer lobe) about three-fourths the length of the first; two 

 setae at distal inner third of first segment; inner lobe of second seg- 

 ment with eight setae graduated in length from outer to inner edge; 

 the outer lobe with four setae. 



Apex of mandible blade (fig. 11) only shghtly expanded and with 

 shallowly incised teeth (fig, 10). Palp with expanded basipod armed 

 with three inner setae; the four segments of exopod well defined, the 

 proximal three with inner seta, the apical with three setae of which 

 the outer is much shorter than the others; fii'st segment of endopod 

 shorter and broader than the apical, with four inner, distally placed 

 setae; apical segment of endopod with two groups of terminal setae, 

 six in the outer group and three in the inner. 



Figures 1-13. — Ridgewayia gracilis, new species, female: 1, Distal part of metasome and 

 urosome, dorsal; 2, habitus, lateral; 3, detail of metasomal wing, lateral; 4, outline of 

 rostrum, ventral, with frontal hairs; 5, leg 5, detail of endopod; 6, leg 5; 7, distal part of 

 urosome and caudal rami, ventral; 8, genital segment, ventral, with detail of operculum; 

 9, leg 1; 10, detail of edge of mandible blade; 11, mandible blade, with palp; 12, leg 2, 

 exopod; 13, leg 4, with detail of marginal armature of inner apical spine. 



