CRUSTACEA OF THE MERGUI ARCHIPELAGO. . D265 
of all, but the second joint. In other respects this species 
almost completely resembles A. brevirostris, for the crests with 
which the outer surface of the larger hand should be provided, 
_ according to the author of the ‘ Fauna Japonica,’ may be perhaps 
visible in very old specimens ; in younger individuals, such as the 
one before me, they are, however, rather indistinct. De Haan 
himself describes the upper crest of the outer surface as “ valde 
obtusa evanida.”’ 
The specimen is 55 millim. long from the tip of the rostrum to 
the end of the terminal seement of the abdomen, and had doubt- 
less not yet reached its full size. The rostrum extends nearly to 
the middle of the carapace; its acute tip projects nearly as much 
forwards as in A. brevirostris, scarcely reaching beyond the middle 
of the antepenultimate joint of the peduncle of the internal 
antenne. The rostrum is acute between the eyes, and is sepa- 
rated from them by rather deep depressions; behind the eyes, 
however, the rostrum is not acute, but rather obtuse. As regards 
the length of the joints of the internal antenne, A. rapaxr fully 
agrees with JA. brevirostris ; the scale of the external antenne 
in the specimen scarcely projects beyond the peduncle of the 
internal antenne. The outer maxillipeds resemble those of 
A. brevirostris, and equally project forwards. 
The right chelipede is the larger, as in the figure of the ‘ Fauna 
Japonica,’ and is 39 millim. long. It therefore appears more 
than twice as long as the carapace, but shorter than the whole 
body—quite as in A. brevirostris. The upper margin of the arm 
of each chelipede is armed with a small acute spine at its distal 
end; the inner margin of the upper surface presents some small 
teeth, of which the distal one is the longest, resembling those of 
the preceding species. The larger hand is 22} millim. long, and 
72 millim. broad near its base, so that it is about three times as 
long as broad; also in the length of the fingers this species 
agrees with A. brevirostris. The shape of the larger hand is 
nearly quite the same in both species, but in A. rapaxr no trans- 
verse groove is found on its upper surface, close to the articula- 
tion of the mobile finger. I may add that in this specimen the 
inner surface of the palm is nearly glabrous. 
The smaller hand is similar to that of A. brevirostris, but 
the palm is comparatively shorter in proportion to the length of 
the fingers, the whole hand being 183 millim. long, the upper 
