CRUSTACEA OF THE MERGUI ARCHIPELAGO. 287 
deeply longitudinally grooved, but is not armed with spinules on 
its lateral margins. 
The first and second pairs of legs are unispinose at the bases, 
and there are no spines on the third pair. In the larger specimen, 
which is apparently an adult, the legs of the third pair extend 
to the distal end of the penultimate joint of the internal antenne, 
being longer than the peduncle of the external antenne. 
This species is apparently closely allied to the Indian P. mono- 
ceros, Fabr., but especially to the Japanese P. curvirostris, 
Stimps. P. Hardwickii, Miers, is probably a mere variety of 
P. sculptilis; for it differs from it only by its rostrum being 
a little more elevated at its extremity, and by the first two post- 
abdominal segments being not at all carinate. 
P. sculptilis has been found also on the shores of Java. 
160. PENEZUS MERGUIENSIS, n. sp. (Pl. XVIII. fig. 8, and 
Pl. XIX. fig. 1.) 
As I have already observed (p. 285), I suspect P. monodon, 
Fabr., will prove to be identical with P. semisulcatus; for 
de Haan’s description agrees perfectly in all its characters with 
those of the ‘ Fauna Japonica,’ and because P. semisulcatus is 
now known to occur algo in the Indian Ocean. 
The species which I now intend to describe is certainly dif- 
ferent from P. semisulcatus, and the distinctive characters between 
both forms will be enumerated below. This new species, however, 
is also closely allied to P. esculentus, Hasw., from Sydney, and 
to P. indicus, M.-Edw. (=P. carinatus, Dana ?), but nevertheless 
it appears to me to be different. The most striking characters 
of P. merguiensis are furnished by the rostrum and by the 
antenne, especially the internal. 
Seven fine specimens (5 3, 2 2) were collected in the Mergui 
Archipelago. The largest specimen and the smallest are females, 
whereas the five males are of an intermediate and nearly equal 
s1ze. : 
The rostrum in most specimens extends quite as far forwards 
as the antennal scales, projecting a little beyond the peduncles 
of the internal antenne ; in the largest specimen, however, it is 
much shorter, reaching only to the distal end of the penultimate 
joint of the peduncles of the upper antenne ; in the smallest 
specimen, on the contrary, (a female), it projects even a little 
beyond the antennal scales. These are, however, only individual 
