REPORT ON THE BRACK YURA. 
13 
penultimate joint of the ambulatory legs. As in Euprognatha rastelli/era, the rostrum, 
on account of the prominence of the median spine of the interantennulary septum, is 
apparently trifid ; hut the spines on the anterior margins of the joints of the ambulatory 
legs, which in Euprognatha rastelli/era are very small, are in this species enormously 
developed on the ambulatory legs of the first pair. The basal antennal joint does not, as 
in most genera of the Inachidse, attain to the frontal margin. 
This genus and the one which follows are among the most remarkable of the Challenger 
Brachyura, and are of especial interest as being Malayasian representatives of a section of 
the subfamily Inacliiiue hitherto represented only by types from Eastern America, and 
which Stimpson 1 separated as a distinct subfamily, Collodinse, on, as I think, insufficient 
grounds. 2 
Platyrnaia wyville-tliomsoni, n. sp. (PI. II. fig. 1). 
Carapace depressed, suborbiculate, with the cervical suture very strongly defined, 
closely granulated over the whole of its upper surface ; some of the granules (e.g.) in the 
median line of the gastric region and on the cardiac and front of the branchial regions 
being of larger size. The median (or interantennulary) lobe of the short rostrum is 
longest and acute ; the lateral lobes very short and obtuse ; the supraocular spines 
small, the postocular longer; behind these there are spinules on the hepatic and ptery- 
gostomian regions and two or three on the sides of the branchial regions in front ; there 
are also lobes, armed with one to four spinules, between the bases of the third and fourth 
and fourth and fifth legs ; the anterior margin of the buccal cavity has a truncated and 
denticulated lobe at its antero-external angle ; the basal segment of the post-abdomen 
(in the female) is granulated and spinuliferous ; the others are granulated only ; the first, 
fifth, and sixth segments longer than the others, the last segment widely transverse ; the 
short basal antennal joint bears two inferior spinules placed near to the distal extremity, 
the two following joints of the peduncle are short, slender, and nearly equal ; both the 
ischium and merus-joints of the outer maxillipedes are spinuliferous on their outer 
surface, and the merus bears also several spinules at and near to its antero-external angle ; 
the chelipedes are about as long as the carapace (with rostrum); merus, carpus, and palm 
thinly setose and spinuliferous; merus with some longer spines on its antero- and postero- 
inferior surfaces ; carpus short, palm about as long as fingers, slightly compressed, nearly 
smooth on its inner surface, fingers slender, straight, acute, and minutely denticulated on 
their inner margins; the first pair of ambulatory legs are (roughly) three and a half 
times the length of the carapace to base of rostrum, with all the joints spinuliferous, the 
spines on the anterior margins of the merus and penultimate joints (usually) alternately 
longer and shorter, the penultimate joint with the spines greatly elongate, rastelliform, 
1 Bull. Mus. Comp. Zool., vol. ii. p. 119, 1870. 2 Vide Joarn. Linn. Soc. Lond., vol. xiv. p. 644, 1879. 
