1 80 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



It is not at all improbable that this genus is tbe same as A. Milne- 

 Edwards's manuscript genus Penccopsis referred to, but not cbaracter- 

 ized by Bate (Ann. Mag. Nat. Hist., V, viii, p. 182, 1881). 



J bave already described two species of tbe genus, H. debilis (Bull. 

 Mus. Comp. Zool., x, p. 91, pi. 15, figs. 6-11, pi. 16, figs. 1-3, 1882) and 

 R. microps (Report U. S. Fisb Com., x, for 1882, p. 413, pi. 10, fig. 1, 

 1884), and I bere add two otbers, wbicb are conspicuously unlike tbem 

 and eacb other. 



Hymenopeiiceus robustus, sp. uov. 



This species is readily distinguished from H. debilis and H. microps 

 by its much greater size, longer rostrum, very large, reniform, and dor- 

 sally flattened eyes, and by tbe pubescence-like clothing of the carapax 

 and pleon. 



The entire surface of the carapax, pleon, and many of tbe appendages 

 is thickly covered with a close velvety coat of very short curved setae. 

 The carapax is slightly compressed, but little bigber than broad and 

 slightly narrowed in front. The hepatic and cervical sutures are deep 

 and the latter is conspicuous, extends nearly to tha middle of the dor- 

 sum, and is marked posteriorly by a high and almost carinate margin. 

 The dorsum is carinated nearly to the posterior bolder, but back of the 

 cervical suture the carina is very low and the dorsum broadly rounded, 

 while in front it gradually rises to the base of the rostrum, which is five 

 to seven eighths as long as the carapax proper, nearly straight, and hor- 

 izontal to near the slightly upturned and unarmed tip, back of wbicb 

 there are six to eight low teeth in front of the orbit and three or four 

 similar ones on the carina of the carapax proper. There is an obscure 

 supraorbital tooth and a stout antennal spine on the anterior margin, 

 wbicb retreats below the latter to the slightly produced inferior angle, a 

 little way back from which there is an acute branchiostegial spine, rather 

 larger than the hepatic and still larger than a small spine a little way 

 back of and slightly above the antennal. 



The eyes are black, reniform, flattened above, and very large, the 

 greatest diameter being from a fourth to a third the leugtli of the car- 

 apax excluding the rostrum. 



The proximal segment of the peduncle of the antennula is fully half 

 as long as the antennal scale, very broad, lamellar, and tbe outer 

 margin armed with a small tooth and its anterior angle spiniform ; the 

 second segment is nearly half as long as the proximal, somewhat tri- 

 quetral, more than half as broad as long, and densely hairy above and 

 on the outer side ; the distal segment is much shorter than the second 

 and subcyliudrical. The antennular flagella are nearly cylindrical, 

 long, and slender, the inferior nearly or quite as long as the carapax in- 

 cluding the rostrum, and its proximal portion densely hairy in the 

 ffl^ile, and the superior mucb longer and nearly naked in both sexes. 

 The antennal scale is two-thirds to three-fourths as long as the cara- 



