CEUSTACEA OF THE MEKGUI AECHIPELAGO. 287 



deeply longitudinally grooyed, but is not armed with spinules on 

 its lateral margins. 



The first and second pairs of legs are unispinose at the bases, 

 and there are no spines on the third pair. In the larger specimen, 

 which is apparently an adult, the legs of the third pair extend 

 to the distal end of the penultimate joint of the internal antennae, 

 being longer than the peduncle of the external antennae. 



This species is apparently closely allied to the Indian P. mono- 

 ceros, Fabr., but especially to the Japanese P. eurvirostris, 

 Stimps. P. Hardioickii, Miers, is probably a mere variety of 

 P. sculptilis ; for it differs from it only by its rostrum being 

 a little more elevated at its extremity, and by the first two post- 

 abdominal segments being not at all carinate. 



P. sculptilis has been found also on the shores of Java. 



160. PENiETJS MERGuiENSis, n. sp. (PI. XVIII. fig. 8, and 

 .Pt-XIX. fig. 1.) 



As I have already observed (p. 285), I suspect P. monodon^ 

 Fabr., will prove to be identical with P. seinisulcatus ; for 

 de Haan's description agrees perfectly in all its characters with 

 those of the ' Fauna Japonica,' and because P. semisulcatus is 

 now known to occur also in the Indian Ocean. 



The species which I now intend to describe is certainly dif- 

 ferent from P. semisulcatus, and the distinctive characters between 

 both forms will be enumerated below. This new species, however, 

 is also closely allied to P. esculentus, Hasw., from Sydney, and 

 to P. indicus, M.-Edw. (=P. carinatus, Dana ?), but nevertheless 

 it appears to me to be dilFereut. The most striking characters 

 of P. merguiensis are furnished by the rostrum and by the 

 antennae, especially the internal. 



Seven fine specimens (5 ^ ,2 5 ) were collected in the Mergui 

 Archipelago. The largest specimen and the smallest are females, 

 whereas the five males are of an intermediate and nearly equal 

 size. 



The rostrum in most sj)ecimens extends quite as far forwards 

 as the antennal scales, projecting a little beyond the peduncles 

 of the internal antennae ; in the largest specimen, however, it is 

 much shorter, reaching only to the distal end of the penultimate 

 joint of the peduncles of the upper antennae ; in the smallest 

 specimen, on the contrary, (a female), it projects even a little 

 beyond the antennal scales. These are, however, only individual 



