CETJSTACEA OP THE MERGUI AECHIPELAGO. 113 



guiabed from Gr. Dussum-ieri, at first sight, by tlie somewlxat 

 different shape of its carapace, especially by the different 

 direction of its margins. Although O. arcuatus has been found 

 in the seas of Japan and New Caledonia, it has not yet been 

 recorded from the Indian Ocean. 



Gelasimus Dussumieri has been recorded from Zanzibar, the 

 coast of Malabar, Java (Samarang), and from New Caledonia ; so 

 that it seems to be distributed throughout the whole Indian 

 Ocean and the Malayan Archipelago. 



The collection of the Leyden Museum contains specimens 

 from Nossy-Faly (near Madagascar), which have been described 

 by Hoffmann (Crustaces de Madagascar, 1874, p. 17) ; but as 

 they differ only from the type of G. Dussumieri in the mero- 

 podites of their ambulatory legs being slightly more enlarged, 

 and in the joints of these appendages being a little less slender, 

 I regard them only as a local race, or possibly individual varieties 

 of this species. 



72. Gelasimus acuttts, Stimps. (PI. YII. figs. 8 & 9, and 

 PI. YIII. figs. 1-4.) 



Gelasimus acutus, Stimpson, Proceed. Acad. Nat. Sci. Philadelphia, 

 1858, p. 99. 



No fewer than sixty-six specimens were collected, namely 

 forty-eight males and eighteen females. Of forty-six specimens 

 the exact locality is not indicated ; the others are from the fol- 

 lowing localities : twelve from Kisseraing, three from King Island, 

 two from Zediwon on the Tenasserim river, two from the bank of 

 Eangoon river, and one from Tavoy. 



This species belongs to the same section of the genus as the 

 last. It was discovered by Stimpson off the coast of China, near 

 Macao, and was established by him for the reception of an im- 

 mature individual, in which the distance between the external 

 orbital angles measured nearly 18 millim., the length of the cara- 

 pace 10 millim., and that of the larger hand about 22 millim. 

 Specimens from the Mergui Collection which present these 

 dimensions fully agree with Stimpson's diagnosis. 



Gelasimus acutus is most closely allied to G. Dussumieri, espe^ 

 cially in the shape of its carapace, but it may be distinguished by 

 the form of the median frontal furrow and at first sight by the 



LINN. JOTJRN. — ZOOLOaX, YOL. XSII. 8 



