48 U.S. NATIONAL MUSEUM BULLETIN 236 



Body cyclopiform (figs. 11a, 12a), cephalo thorax ovoid, abdomen 

 slender, proportional lengths 33:24. Head and 1st thoracic somite 

 completely fused to form cephalic somite and occupying considerable 

 part of cephalothorax. Cephalic somite considerably flattened dorso- 

 ventrally, in lateral aspect with smoothly curved back (fig. 11a). 

 Head broadly rounded in lateral view, curved imperceptibly into 

 rostral plate. Lateral parts of cephalic somite slightly but distinctly 

 produced to shield oral appendages. Posterolateral corners of ce- 

 phalic somite slightly produced and rounded. In dorsal aspect fron- 

 tal part of cephalic somite broadly and uniformly rounded, outline of 

 head forming almost complete semicircle, greatest diameter behind 

 middle. Kostrum not visible from above or from side; appears in 

 ventral aspect as backward directed plate, broadly triangular, between 

 basal portions of antennules. Apex of rostral plate produced into 

 single fine filament (fig. 12/). 



Body between thoracic somites contracted, with the result that 

 somites stand out very clearly; contraction deepest between somites 

 3 and 4. Thoracic somites 2 and 3 have about same length, 4th 

 thoracic somite being much smaller. Lateral borders of somites 2 

 and 3 cut off almost squarely in dorsal and lateral aspect; lateral 

 borders of somite 4 in dorsal view rounded, in lateral aspect slightly 

 produced backward and rounded. 



5th thoracic somite as broad as 4th but distinctly longer; insertion 

 of feet laterodorsally, with the result that 5th legs point obliquely 

 upward. Genital somite slightly shorter than combined length of 

 abdominal somites 3 to 5, composed of fused somites 1 and 2. In 

 dorsal aspect (fig. 126) it h as a curious top-shaped appearance by the 

 presence of a lateral swelling on each side, each swelling being obtusely 

 pointed. Genital apertures laterally closed by plates that are dis- 

 tinctly visible in lateral aspect of somite, slits continuing dorsally as 

 shallow ridges (fig. 12c). There is another pair of ridges on the distal 

 part of the genital somite representing the lines of fusion between 

 abdominal somites 1 and 2; these run from mediocaudally to latero- 

 ventrally. No dorsal or ventral swellings on genital somite (figs. 126, 

 c). Abdominal somites 3 and 4 and anal somite of nearly same 

 length, anal somite with small, proximally placed operculum. No 

 spinules or hairs along distal portions of abdominal somites. 



Furcal rami nearly 3 times as long as broad (proportion 8:3), each 

 ramus with 5 marginal setae. Setae 1, 4, and 5 are only slightly 

 longer than furca, seta 5 inserting subapically. Setae 2 and 3 elon- 

 gated and slightly thickened; they reach % length of abdomen. This 

 female specimen carries two elongated, oval sacs, attached laterally, 

 containing numerous small eggs. 



