44 



PROCEEDINGS OF THE NATIONAL MUSEUM 



Measurements. — (In mm) 10 females and 10 males: 



female 



Total length, excluding caudal setae 



Length of cephalothorax, including frontal 

 region 



Width of cephalothorax 



Length of genital segment, excluding gen- 

 ital flap 



Width of genital segment 



Length of abdomen 



Length of alae (N = 9 in female) 



Length of genital flap 



Length of caudal rami 



Length of egg strings (4 strings) 



male 



9. 13 7. 50-10. 50 



Remarks. — Two sets of descriptions are given below, the first for 

 the matui-e adult, the second for the immature adult. The author 

 feels that the changes that occur in the adult life history stage, as 

 indicated in the measurements, may have caused some confusion in 

 the taxonomy of the genus. The bases for this behef are given in 

 the discussion section, following the description of the species. 



Description. — (Mature adult): Female cephalothorax (fig. 16a) 

 ovoid, consisting of cephalon and first 4 thoracic segments. Frontal 

 region distinct, length approximately one-twelfth that of entire cepha- 

 lothorax, with median cleft and narrow membrane along anterior mar- 

 gin. Lateral cephalothoracic margins with indentation medially, 

 distinct in some specimens, indistinct in others; margin with fine 

 membrane. Posterior lateral cephalothoracic region broadly rounded, 

 extending past median posterior region, with socket-like depression 

 (not figured); posterior sinus (fig. 16c) distinct, U-shaped, with fine 

 membrane along outer margin. Median-posterior region with pair 

 of small lobes laterally. Major dorsal cephalothoracic grooves form- 

 ing irregular H, anterior legs extending past indistinct ocular region 

 (ocular region not figured). Dorsal cephalothoracic surface without 

 plumosities but with minute, spikelike irregularities laterally and 

 small denticulations posteriorly. 



Free fourth pedigerous segment, excluding alae, approximately one- 

 fifth width of cephalothorax, widest medially, at origin of fourth 

 thoracic legs. Alae sharply indented on median lateral margin, 

 extending posteriorly over anterior end of genital segment. Divi- 

 sion between fourth pedigerous and genital segments distinct, demar- 

 cated ventrally by ridgelike transverse projection. 



Female genital segment (fig. 16(7) of variable shape, narrow anteri- 

 orly in some specimens, broad in others, posterior dorsal surface with 

 pair of lateral lappets, lappets distinct from segment. Dorsal sur- 

 face of segment lightly rugose, extending laterally slightly past ven- 



