34 
THE VOYAGE OE H.M.S. CHALLENGER. 
Two small males of this well-known species, the “giant crab” of the Japanese Seas, 
were obtained at this Station ; the dimensions of the larger specimen are (roughly) as 
follows : 1 — 
Adult . 
Inches. 
Centms. 
Length of carapace and rostrum, about 
9 
23 
Width over back at the branchial regions, nearly 
7 
718 
Length of a chelipede, rather over 
11 
28 
Length of first ambulatory leg, rather over 
20 
51 
The tubercles and spines of the carapace are disposed much as in the large adult 
males, but are somewhat more acute, especially on the sides of the branchial regions ; 
the chelipedes are comparatively small and slender, as in De Haan’s figure. In both 
specimens the boss or tubercle upon the fifth segment of the post-abdomen is large and 
prominent. Both specimens are infested with numerous examples of a pedunculated 
Cirripede. 
Subfamily 3. Acanthonychina:. 
AcanthonychineR, Miers, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 647, 1879, et synonyma. 
Eyes small and immobile or partially retractile, and usually concealed beneath the 
prominent prseocular spine. Postocular spine small or absent. Basal antennal joint 
usually enlarged at the base and narrowing distally ; rarely so slender as in Inachus. 
The carapace is somewhat oblong or subtriangulate, rarely elongated and narrow. 
Rostrum simple or bifid. Merus of the exterior maxillipedes distally truncated. The 
chelipedes usually have the palms compressed. The ambulatory legs are of moderate 
length. 
Besides the new genus Oxypleurodon, described below; Sphenocarcinus, A. Milne 
Edwards, which in 1879 I referred to the Pericerinse, should perhaps be placed in this 
group. 
Huenia, De Haan. 
Huenia, De Haan, Crust, in v. Siebold, Fauna Japonioa, dec. 4, p. 83, 1839. 
„ Miers, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 643, 1879. 
Carapace depressed, flat above and dissimilar in the two sexes ; in the male it is 
elongate-triangulate, usually with one pair only of lateral lobes (the lateral epibranchial 
lobes) ; in the female there are, besides these lobes, which are largely developed, always 
an anterior pair situated upon the sides of the hepatic regions ; the carapace is thus 
quadrilobated ; there is a small prseocular, but no postocular spine. Rostrum simple, 
acute, vertically deep and laterally compressed. Post-abdomen in the male seven -jointed ; 
1 These measurements were taken with a tape over the convexities of the carapace and limbs, not, as in other 
species, with compasses. 
