CRUSTACEA OF THE MERGUI ARCHIPELAGO. 59 
These specimens agree very well with the description and 
figure given by Milne-Edwards, but I may add the following 
details. 
In all the eight specimens the upper margin of the orbits is more 
or less granular, and presents two fissures, so that this species 
belongs to the subgenus Hupilumnus, established by Kossman 
(Mr. Miers, /.c., erroneously mentioned the subgenus sensu stricto 
Pilumnus). Inall the under margin of the larger hand is covered 
with rounded granules, except in the two largest males, in which 
the granulation of the under surface of the larger hand gradually 
begins to disappear. According to Dr. Hilgendorf (J. c.), in the 
true P. vespertilio the under surface of the larger hand is some- 
what granular in the male but everywhere granular in the female, 
so that there can be no doubt that these specimens are really 
representatives of this species. 
Pilumnus ursulus, Ad. & White, and Pilumnus mus, Dana, are 
identical with this species, according to Mr. Miers. 
Pilumnus vespertilio is a very common species, distributed 
throughout the whole Indo-Pacific region, having been observed 
in the Red Sea (Kossmann), at Mozambique (Hilgendorf), Java 
(Miers), Sydney (Hess), and on the coral-reefs of Australia 
(Haswell), at New Caledonia, the Loo-Choo Islands, and Japan 
(Stempson). 
41. Prnumyus ANDERSONI, n. sp. (PI. III. figs. 5 & 6.) * 
Four specimens (16, 3 2) of this new species were collected 
by Prof. Anderson in the Mergui Archipelago, two of which were 
found at Elphinstone Island and two at King Island. One of the 
female specimens is provided with eggs and another is infested in 
its cephalothorax with a Bopyrus. Courage, indeed, is necessary 
to describe a new species of this genus, for the very numerous 
species of Pzlumnus, which often closely resemble one another, 
are rather insufficiently known. I therefore sent a specimen to 
Prof. Milne-Edwards, who informed me that this species was 
unknown to him, although closely allied to Pelumnus Peronii, 
M.-Edw., as I also supposed. As regards the species which 
have been described by Stimpson, Hilgendorf, Miers, and Has- 
well, I may remark that P. Anderson is allied to P. hirsutus, 
Stimps., P. longicornis, Hilg., P. Bleekeri, Miers, P. terre- 
regine, Hasw., and P. vestitus, Hasw., but is nevertheless a 
distinct species In my opinion. 
