CRUSTACEA OF THE MERGUI ARCHIPELAGO. 83 
not only because the typical specimens of Fabricius and Herbst 
have never been examined by later carcinologists, but also be- 
cause the numerous species are often only distinguished by 
very slight differences. JI therefore consulted Prof. Milne- 
Edwards regarding this species, and I was informed by him that 
it is closely allied to G. quadrimaculatum, A. M.-Edw.* It 
differs, however, from G. guadrimaculatum (1) by the form of the 
antero-lateral teeth, the last of which is distinctly longer than 
the preceding, not only in young specimens but even in the adult ; 
and (2) by the carpopodites of the natatory legs being armed with 
an acute spine, and by other characters. 
This species is probably identical with G. spiniferum, Miers, 
from North-eastern Australia, which was, without doubt, estab- 
lished upon a young specimen. In the latter the outer surface 
of the carpopodites of the anterior legs is armed with only two 
spinules, and the posterior margin of the penultimate joint of the 
natatory legs is not denticulated ; whereas in equally young spe- 
cimens, and indeed in all the twenty specimens of the Mergui form, 
there are three spinules, and denticulations are distinctly present. 
I therefore prefer to describe the Mergui crab as a new species, 
but a renewed examination of the species from Port Molle may 
perhaps prove its identity with G. merguiense. 
I may further add that, according to Milne-Edwards, G. acutum 
from Japan is a distinct species. 
The Collection contains a fine series of twenty specimens of 
various sizes of the new species, nine of which were found at 
* A close examination of the typical specimen of Fabricius’s Portunus lucifer 
(Suppl. Entom. p. 864) led me to the conclusion that it is identical with Gonio- 
soma quadrimaculatum, A. M.-Edw. I also received from Prof. Mobius the 
type specimen of Fabricius’s Portunus annulatus, which is much smaller than 
the type of P. lucifer. Iam much inclined to regard P. annulatus as only a 
younger specimen of P. lucifer, for I scarcely find any other differences than that 
the cephalothorax of the latter is a little more enlarged than in the former, 
and that the antero-lateral spines and those of the anterior legs are less acute 
than in P. annulatus, characters which probably may be due to the greater age 
of the type of P. ducifer. The carpopodite of the natatory legs in P. lucifer, as 
in P. annulatus, is quite unarmed, but the propodite is denticulated along its 
posterior margin. In both species the last antero-lateral tooth is the smallest. 
I may further add that an examination of the typical specimen of the Gonio- 
soma described by Heller as G. orientale (Novara Reise, p. 29, t. iii. fig. 3), has 
proved it to be identical with P.annulatus, Fabr. The fine violet rings on the 
legs are still visible, almost as distinctly as in the dried specimen described by 
Fabricius. G. Hellerit, A. M.-Edw. (1867), is probably a different form. 
6* 
