CRUSTACEA OF THE MERGUI ARCHIPELAGO. 289 
the internal longitudinal margins are curved upward, as in 
P. indicus. 
The internal antennew are closely similar to those of P. semi- 
sulcatus; but the internal flagellum is a little shorter than the 
external. The peduncle is constantly a little shorter than the 
antennal scales. The external flagellum is much longer than the 
peduncle, z. e. the distance between the distal end of the terminal 
joint and the frontal margin of the carapace, and when laid 
backwards it reaches to nearly the first tooth of the rostrum ; as 
in P. semisulcatus, this flagellum is broad and hollowed along 
the proximal third of its length. The inner or under flagellum is 
cylindrical and shorter than the other, and does not reach to the 
anterior margin of the carapace when laid backwards. The length 
of the flagella of the internal antenne distinguishes this species 
at first sight from the Australian P. esculentus, Hasw. The 
flagella of the outer antenne are almost twice as long as the 
whole animal. 
The external maxillipeds are longer in the male than in the 
female; in the male they are as long as the peduncle of the 
internal antenne, and reach almost to the distal end of the an- 
tennal scales; whereas in the female they are much shorter, and 
scarcely extend beyond the distal end of the antepenultimate 
_ joint of the peduncle. 
The legs of the first pair are a little longer than the peduncle 
of the external antenne, but do not project beyond the eyes; 
their® carpopodites are nearly once and a half as long as the 
hands (the palm and the fingers taken together). They are 
armed with a spine on the under surface of their second joints, 
and with another spine on the under surface of their third joints, 
just as in P. semisulcatus, de Haan, and in P. esculentus, Hasw. 
The legs of the second pair scarcely reach to the distal end of 
the penultimate joint of the peduncles of the internal antenne ; 
their carpopodites are hardly more than twice as long as the 
hands, and they are armed with a spine on the under surfaces of 
their second joints. The legs of the third pair are the longest of 
all; in the largest specimen they scarcely extend beyond the 
antennal scales, but in the male specimens the fingers almost 
reach beyond them. Their carpopodites, in the largest specimen, 
are precisely twice and a half as long as the hands, but in the 
younger specimens they are a little more. The legs of the fourth 
pair are a little longer than the peduncle of the external antenne ; 
LINN. JOURN.—ZOOLOGY, VOL. XXII. 19 
