82 U.S. NATIONAL MUSEUM BULLETIN 236 



with the result that oral parts are freely visible in lateral aspect 

 (fig. 24). Rostral base visible in dorsal aspect, separated from ce- 

 phalic somite by groove; in lateral aspect visible as cm'ved plate, 

 slightly shorter than 1st antennular segment, pointing obliquely 

 downward and forward, in sharp contrast to condition found in 

 H. conjusus. Epimeral plates of thoracic somites 2 to 4 rounded, 

 somites 2 and 3 of about same length; 4th thoracic somite shorter, 

 in lateral aspect broadly rounded. 



5th thoracic somite visible in dorsal aspect as narrow band; in 

 lateral aspect it is better marked. Abdominal somites 1 to 4 of 

 nearly same length; somites 1 and 2 separate. Somite 1 with, on 

 both sides, lateroventral row of spinules at distal end of somite; 

 somites 2 and 3 have a completely closed row of fairly coarse spi- 

 nules at their distal margins. Abdominal somite 4 with some ventro- 

 caudal spinules. Anal somite distinctly shorter than preceding 

 somites; anal flap just visible in lateral aspect; some spinules are 

 found near flap. 



Furcal rami twice as broad as long, with 5 marginal setae and 1 

 appendicular seta each. Appendicular seta and setae 1, 4, and 5 of 

 moderate length; setae 2 and 3 lengthened and thickened, especially 

 2nd, which reaches fi length of body. 



Antennules chirocerate, 5th segment swollen, almost globular, with 

 distinct basal tooth and finely crenulated lamella; apical segment 

 small. The setation has been represented in figure 25a; there are 2 

 aesthetascs, one on segment 4 and one on segment 5, but one of the 

 setae on the apical segment is thickened and may have a sensory 

 function. 



Antenna (fig. 256) with allobasis and single endopodal segment. 

 Exopodite smaU, 2-segmented, basal segment with 2, apical with 4, 

 setae. Allobasis with single internal seta. Endopodite with 3 spines, 

 4 geniculate setae, and a fine appendicular seta. 



I failed to obtain a suitable preparation of the mandible. 



Maxillule (fig. 25c) as in H. chelifer; arthrite of praecoxa with 6 

 teeth, strong basal seta, and 2 fine apical setae. Coxal endite well 

 developed, bearing 2 setae. Basal endite small, bearing 1 strong 

 seta and 1 fine seta; basipodite with 3 setae. Whole endopodite 

 reduced to form single segment with 3 setae. Exopodite styliform, 

 with 3 setae. 



Maxilla small (fig. 2bd), articulation indistinct; 2 praecoxal, 1 

 coxal, and 1 larger basal endite. Praecoxal and basal endites each 

 with 2 plumose setae. Basal endite with strong, curved spine, co- 

 alescent with lobe; in addition, there is a seta. Endopodite almost 

 completely reduced and represented by 4 setae at base of spine. 



