122 U.S. NATIONAL MUSEUM BULLETIN 236 



Body of the general shape characteristic for this genus, strongly- 

 compressed dorsoventrally, in outline broadly ovoid, shaped like a 

 shield (fig. 40). Body, in lateral aspect, almost straight, but ven- 

 tral surface is concave; oral parts and legs (with the exception of 

 leg 5) situated in ventral cavity. Head and 1st thoracic somite 

 fused to form cephalic somite. Anterior part of cephalic somite 

 rounded, almost semicircular, slightly produced between basal parts 

 of antennules and supporting a distinctly visible rostral base; dis- 

 tally cut off squarely (fig. 43a). Rostrum invisible from above, 

 pointing downward, triangular, apex blunt. 2nd and 3rd thoracic 

 somites of about same length, epimeral plates well developed (exact 

 shape can best be judged from figure 40); 3rd with hairlike spine on 

 each side. Cephalic somite and epimeral plates of thoracic somites 

 2 and 3 with a narrow hyaline lamella. 4th thoracic somite visible 

 from above, but epimeral plates are undeveloped. 



5th thoracic somite visible in dorsal aspect as narrow strip, to 

 which wing-shaped 5th legs are attached. Abdomen composed of 

 two parts, big genital complex and small anal part, each apparently 

 resulting from fusion of some somites (fig. 436). Anal complex with 

 slightly concave lateral walls, backwardly produced into pointed 

 wings, reaching half length of furcal rami. Anal complex small, in 

 preserved specimens curved under body, but carefully stretched in 

 figmred female; anal complex fits, with part of furcal rami, in depres- 

 sion formed by lateral wings of genital complex, and has triangular 

 anal flap with rounded apex. 



Furcal rami lamellar, twice as long as broad, internal margin 

 straight, external margin convex, with the result that greatest diameter 

 is at about half its length ; extreme apex cut off squarely. 5 short mar- 

 ginal setae and 2 appendicular setae inserting on surface of each 

 ramus. Position of marginal setae can best be judged from figure 

 436; the appendicular setae insert close together on the lateral part 

 of the upper half of each ramus. Between the marginal setae the 

 margin is haired. 



5th legs, in a dorsal view of the whole body, appear as wing-shaped 

 structures, of which the apex reaches halfway along the furcal rami. 

 There is a distinct longitudinal carina on the legs, the external mar- 

 gin fringed with spiniform hairs; there are two short setae, the posi- 

 tion of which will be indicated below. 



The whole carapace has a characteristic reticulated appearance 

 ("malleatus"= hammered) as though the integument is covered by 

 small, hollowed depressions, giving the carapace a malleated appearance. 

 This very distinctive pattern is best developed on the cephalic somite 

 and gradually disappears caudally on the thoracic somites. At the 

 antennular bases there is, on each side, a cup-shaped cuticular 



