CRUSTACEA OF THE MERGUI ARCHIPELAGO. 19 
the prolongation of the oblique surface of the anterior declivity 
of the gastric region. In the largest specimen (15 millim. long), 
_amale, the cephalothorax is 10 millim. long; so that the pro- 
portion of the length of the cephalothorax to that of the rostral 
spines is nearly as 15 to 7, whereas in H. Hilgendorfi this pro- 
portion is as 15 to 117; the spines are thus comparatively 
much longer in this species. The posterior cardiac lobe rises 
into an acute spine. 
Genus Naxia, If-Hdw. 
6. Naxra (NaxtorpEs) Perersi1, Hilgendorf. 
Podopisa Petersii, Hilgendorf, Monatsb. Acad. Wissensch. Berlin, Nov. 
1878, p. 785, Taf. i. fig. 1-5. 
Naxia (Naxioides) Petersii, Miers, Report on the Zool. Collections made 
in the Indo-Pacific Ocean during the Voyage of H.M.S. ‘ Alert,’ 1884, 
p. 923. 
A young female specimen of this species was forwarded to 
Dr. Anderson from the Andaman Islands, and I therefore 
includeit. As it agrees completely with Hilgendorf’s description 
and tigure, I will only add the following remarks :—The spine 
on the intestinal region appears rather obtuse, whereas in 
Hilgendorf’s adult specimen it is more acute. As in his speci- 
men, the spines of the rostrum seem to be broken off; they 
have almost the same length, are nearly parallel to one another, 
and are comparatively shorter than in the specimen in the 
Berlin Museum, for they do not reach as far forward as the 
pedunele of the external antenne. Each spine is armed on its 
dorsal surface with a very small accessory spine, somewhat as 
in Naxioides hirta, A. M.-Edw. These antennal peduncles, which 
in the Berlin specimen were unequally developed, are quite 
equal to one another in the Andaman specimen; their terminal 
joint is little more than half as long as the penultimate joint, 
and the flagella are scarcely so long as the two terminal joints 
taken together. The flagella bear a few long hairs on their 
inner side; and the two last joints of the peduncle are clothed 
with many hooked hairs. 
The anterior legs are comparatively much smaller than in the 
male, but present nearly the same form. The length of the 
cephalothorax to the base of the rostral spines is about 26 millim., 
and the distance between the tips of the posterior branchial 
spines, indicating the greatest width of the carapace, amounts to 
o% 
