4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 9I 



narrower than the genital segment and without dorsal plates. Genital 

 segment nearly as long as the three free thorax segments combined, 

 narrowed anteriorly and widened posteriorly, the posterior corners 

 distinctly bilobed, the inner lobes projecting backward on either side 

 of the abdomen. Spermatophore receptacles large and elliptical, each 

 containing a single spermatophore with a long coiled tube. 



Appendages like those of the female with the usual sexual modifica- 

 tions. In the first maxilla (fig. 13) the tip on the anterior margin 

 projects strongly and its two segments are much larger than in the 

 female ; the ventral palp also forms a distinct lobe with the two 

 processes on its upper margin. The second maxilla is exactly like 

 that of the female except that its terminal claw is not as sharply 

 pointed (fig. 14). In the maxilliped just inside the cup-shaped promi- 

 nence on the distal margin of the end segment are two hemispherical 

 protuberances with rough surfaces (fig. 30). When the claw shuts 

 down, it lies between these protuberances with its tip inside the cup 

 and is thus held rigidly in place. 



The arrangement of the spines and setae on the swimming legs is 

 as follows. First exopod i-o, 4-3; endopod o-i, 0-3. Second exopod 

 i-i, 4-4; endopod o-i, 0-5. Third exopod i-i, 3-6; endopod 0-0, 0-7. 

 Fourth exopod 4-4 ; endopod 0-4. 



Total length 5 to 6.5 mm. Width of cephalothorax 3 to 4 mm, length 

 on the midline 2.38 mm. 



Remarks. — 'Heller's description and figures of the female of this 

 species show that he did not have fully matured specimens, and no 

 other author has even mentioned the species except Bassett-Smith. 

 As the females carrying egg strings dift'er somewhat from Heller's 

 immature specimens, a new description will be published later. 



NESIPPUS GRACILIS, n. sp. 



Plate 2, figs. 15-27; plate 3, fig. 33 



Occurrence. — Three females and six males of another species of 

 Nesippus were obtained from the same hosts in company with the 

 preceding specimens. They are smaller in size and quite different in 

 structural details, and since in the female the genital segment, like 

 that of cryptiirus, has long and broad posterior lobes which conceal 

 the abdomen and caudal rami in dorsal view, the specimens cannot 

 be referred to any described species but must be established as new. 



Types. — Females, U.S.N.M. no. 64055; cotypes : males, U.S.N.M. 

 no. 64056. 



