CRUSTACEA OF THE MEBGUJI ARCHIPELAGO. 281 



from the Sandwich Islands is a distinct species, then the 

 Mergui specimens should certainly be referred to Stimpson's 

 P. honinensis. 



The largest specimen, a male, is 85 millim. long from the tip 

 of the rostrum to the end of the terminal postabdominal segment. 

 In this specimen the carapace is a little rough anteriorly, being 

 covered with minute spinules, arranged irregularly and only 

 visible with a magnifying-glass ; on the posterior half of the 

 cephalothorax these spinules are not found, the upper surface being 

 only minutely punctate. In the other younger specimens these 

 minute spinules are much less numerous, being still only 

 observed on the antero -lateral parts of the carapace, or they are 

 even quite absent, the cephalothorax then being smooth. 



The rostrum is characteristic. It is quite similar to that of 

 P. superbus, Heller (Novara-Eeise, Taf. x. fig. 10), but in this 

 species it is generally shorter than the antennal scales and not 

 longer. In most specimens, as, indeed, in the largest, the rostrum 

 does not reach to the end of the antennal scales, being a little 

 shorter than these appendages, but it exceeds the peduncles of the 

 internal antennae : in the smallest individual, which is only 40 

 millim. long, the rostrum is even a little longer than the antennal 

 scales ; whereas in the specimen from Elphinstone Island it is only 

 just as long as the peduncles of the internal antennae. In most 

 specimens it is a little convex above the eyes and slightly directed 

 downwards at the distal end, sometimes, however, it is a little 

 curved upwards towards the latter. The rostrum is ^|^^ toothed ; 

 in the largest specimen the formula is ~, in four other specimens 

 ^, and in the specimen from Elphinstone Island the rostrum is ^^ 

 dentate. In the specimens which were collected by Dana at 

 the Sandwich Islands the formula was ^4^, Ijut this difference 



4—0 ' 



may be regarded at most as indicating a local variety. The 

 teeth of the upper margin are small and nearly equidistant ; the 

 first four teeth are placed on the carapace behind its anterior 

 margin, the first tooth is found at a distance of a third of the 

 length of the cephalothorax from its anterior margin and the 

 teeth occur quite to the tip of the rostrum. (In Dana's figure 

 1 a six teeth are shown as occurring behind the anterioi 

 margin of the carapace; but this figure is certainly incorrect, 

 twenty teeth having been figured on the upper margin.) 



The external maxillipeds are of moderate length, being only 



