Mr. E. J. Miers on Malaysian Crustacea. 309 



mobile finger; and I regard it as very probable that it is merely 

 a variety of that species. There is, as in G. vocans, a strong 

 triangular tooth at the distal end of the upper margin of the 

 arm ; the palm is strongly granulated in the middle of its 

 outer surface, and there is a well-marked concavity on the 

 outer surface at base of the lower finger in both forms. 



The relative length of the fingers as compared with that of 

 the palm is clearly a character that varies with the age of the 

 individual, the fingers being always shortest in the smallest 

 examples. The upper finger is never longitudinally sulcated, 

 either in G. vocans or G. Marionis. 



Gelasimus arcuatus. 



Gelasimus arcuatus, De Haan, Faun. Japon. Crust, pp. 53, 261, pi. vii. 



fig. 2 (1835). 

 Gelasimus tenuimanus, White, List Crust. Brit. Mus. p. 35 (1847), 



siue descr. 



Borneo (an adult male). 



In what I regard as the typical condition of this species, 

 the fingers of the larger hand are greatly elongated and with- 

 out prominent lobes on their inner margins. They are often 

 nearly three times the length of the hand. 



Gelasimus arcuatus, var. forcipatics. 



Gelasimus forcipatus, Ad. & White, Zool. Samaraug, Crust, p. 50 

 (1848) ; 'M.-Edw. Ann. Sci. Nat. (ser. 3) Zool. xviii. p. 147 (1852). 



? Gelasimus brevipes, M.-Edw. /. c. p. 146, pi. iii. fig. 7 (1852). 



? Gelasimus rubripes, M.-Edw. I.e. p. 148 (1852); Jacq. & Lucas, Voy. 

 Pole Sud, Zool. iii. Cr. p. 66, pi. vi. fig. 2 (1853). 



Batjan (seven males, of different sizes). 



In all the specimens I refer to this variety the fingers are 

 shorter, not exceeding twice the length of the palm, and nearly 

 always lobed or toothed on their inner margins. In the 

 smaller examples the length of the fingers is relatively less ; 

 and in the smallest they are not half the length of the palm. 



In the largest of the specimens from Batjan there is (besides 

 the granulations with which the inner margins of the fingers 

 are always armed) a single tooth on the lower finger ; in three 

 others, one on the upper and none on the lower; in two others, 

 two on the upper and one on the lower ; while in the smallest 

 the teeth are obsolete. The width of the merus of the 

 ambulatory legs also appears to vary somewhat in this 

 species. 



G. arcuatus may always be distinguished from G. vocans 

 by the absence of the strong triangular tooth at the distal end 

 of the arm, its place being taken by a series of granules ; the 



