CRUSTACEA OF THE MERGUI ARCHIPELAGO. 145 
The upper surface of the thumb, which in these specimens appears 
a little more arcuate than in the figure 2 ¢ of Hilgendorf, is 
minutely tubercular, especially near the inner surface, nearly to 
the tin. The inner surface of the palm presents on its proximal 
half some rugose lines, which are parallel to the posterior margin, 
and the inner surface of the index is a little granular at the 
base. 
Metopograpsus messor has been found in the Red Sea, through- 
out the whole Indian Ocean (Zanzibar, Persian Gulf, Nossy-Faly, 
coast of Malabar, Mauritius), in the Malayan Archipelago, and 
extending from Australia to the Fiji Islands, New Caledonia, and 
the Sandwich Islands. 
82. Mrroroarapsus Macunatus, H. I-Hdw. (P1.X. figs. 1-3.) 
Metopograpsus maculatus, H. Milne-Edwards, Ann. Sci. Nat. 3° série, 
t. xx. p. 165. 
Four specimens were collected in the Mergui Archipelago, one 
male and three females. 
This species is still very imperfectly known, for so far as I 
am aware no other description has been published since its first 
diagnosis, given by the late H. Milne-Hdwards. Prof. A. Milne- 
Edwards, to whom I had sent the male individual of this collec- 
tion, informed me that it was JZ. maculatus, M.-Edw., as I had 
inferred. I will therefore point out some characters of this 
Metopograpsus and compare it with J. messor, Forskal, and 
M. pictus, A. M.-Edw., the latter of which occurs in the seas 
of the Moluccas and on the shores of New Caledonia. 
With respect to the general shape of the cephalothorax, 
M. maculatus appears quite intermediate between the two above 
mentioned species of this genus, as regards the proportion between 
the length and the breadth of the carapace. The cephalothorax 
of M. maculatus is somewhat less enlarged and somewhat more 
elongate than that of JZ. messor; in the male specimen from 
Mergui being even more slightly enlarged anteriorly than in 
the typical specimens from Java, described by the late H. Milne- 
Edwards. As Prof. A. Milne-Edwards informs me, the pro- 
portion of the distance between the external orbital angles to 
the length of the carapace is as 80: 23 (in IL messor as 80 : 22). 
The carapace of WM. pictus is much more elongate than that of 
M. maculatus. 
As I have already observed, the front is a little more enlarged | 
LINN. JOURN.—-ZOOLOGY, VoL. XXII. | 10 
