56 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
Posterior sinus (fig. 22c) distinct, frequently closed posterly; outerior 
margin bearing fine membrane, dorsal cephalothoracic surface adjacent 
to anterior and inner surfaces of sinus with minute, ridgelike roughen- 
ings. Posterior surface of median cephalothoracic region projecting 
slightly past posterior surfaces of lateral cephalothoracic regions, 
division between free fourth pedigerous segment and cephalothorax 
distinct. Major dorsal cephalothoracic grooves forming irregular H, 
anterior legs terminating well posterior to distinct ocular region present 
on median longitudinal axis of body, in anterior third of cephalothorax. 
Free fourth pedigerous segment subtriangular, anterior region 
narrowest; medial constriction evident in some specimens, not in 
others; fourth pedigerous and genital segments fused. Genital segment 
(fig. 22b) narrow anteriorly, broad posteriorly, lateral margins strongly 
convex anteriorly, almost parallel posteriorly. Fifth leg (fig. 239) 
situated on ventral posterior surface, consisting of slight swelllng 
bearing nodule with 3 plumose setules. Genital segment and abdomen 
fused. 
Abdomen 1-segmented, broad anteriorly, narrower posteriorly, 
lateral margins flatly convex. Caudal rami (fig. 22d) attached to 
posterior ventral surface of abdomen, paddle-shaped, distal inner 
surface plumose. Distal surface of rami bearing 3 plumose setae and 
1 plumose setule, additional plumose seta and setule present on 
slight indentation of middle of outer lateral surface. 
Antennule (fig. 22e) 2-segmented, attached to knoblike cuticular 
projection of lateral anterior ventral surface of cephalothorax. First 
segment subrectangular, approximately two-thirds the length of 
second segment, anterior ventral and anterior surfaces with 21 naked 
or lightly plumose setules and setae; second segment rodlike, with 
naked setule from distal third of posterior surface, 11 naked setules 
from distal surface. Antenna (fig. 22f) 3-seemented, situated posterior 
and medial to antennule base. First segment flattened, irregular 
in outline; second segment subrectangular, with small, subtriangular 
projection from outer anterior surface. Third segment and terminal 
process indistinctly separable, clawlike, with setule-like accessory 
process medially, at junction of segment and terminal process; addi- 
tional, lobate process present on proximal portion of segment. 
Mandible (fig. 22f) rodlike, 4-parted, distalmost part flattened, 
curved inward, with 12 denticulations along inner surface. Postanten- 
nal process (fig. 22f) situated posterior and lateral to antenna base, 
consisting of plate bearing posteriorly directed spine and shorter, 
medially directed spine; 3 nodules present, 2 on plate, third slightly 
posterior to plate, all with several hairlike processes. Postoral process 
(fig. 22f) with broad base, irregularly tapered to bifid distal end, inner- 
most tine approximately one-third the length of outer. Maxillule 
