CEirSTACEA OF THE MERauI AECHIPEIAGO. 289 



the internal longitudinal margins are curved upward, as in 

 P. indicus. 



The internal antennse are closely similar to those of P. semi- 

 sulcattis; 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, i. 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 antennse distinguishes this species 

 at first sight from the Australian P. esculentus, Hasw. The 

 flagella of the outer antennse 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 antennse, 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 antennse, 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 antennse ; 

 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 antennse ; 



LINN. JOUEN. — ZOOlOaT, YOL. XXII. 19 



