242 
THE VOYAGE OF H.M.S. CHALLENGED. 
The nearest ally to this genus is Heloecius, Dana, which is distinguished by the equal 
chelipedes and somewhat differently shaped post-abdomen of the male, which is broader 
at the base, &c. 
The genus Acanthoplax, Milne Edwards, is united by Kingsley with Gelasimus, and 
cannot, I think, be regarded as more than a subgenus ; it is distinguished, according to 
Milne Edwards, merely by having the branchial regions of the carapace armed with, a 
marginal series of large spiniform tubercles. 
Gelasimus vocans (Linne). 
1 1 Cancer vocans, Linne, Syst. Nat., ed. xii. p. 1041, 1766. 
Gelasimus vocans, Milne Edwards, Ann. d. Sci. Nat., ser. 3, Zool. xviii. p. 145, pi. iii. fig. 4, 
1852, nec. Hist. Nat. Crust. 
Gelasimus nitidus, Dana, TJ.S. Explor. Exped., voL xiii., Crust., p. 316, pi. xix. fig. 5, 1852. 
Fiji Islands, Kandavu (an adult male) ; Arrou Islands (an adult male). 
The form thus designated is distinguished by the form of the larger chelipede in the 
male, whose palm is coarsely and strongly granulated externally, with the pollex or lower 
finger externally concave at the base, and bearing two strong triangular lobes, situated, one 
at about the middle of its inner margin, and one near to the distal extremity (besides a 
smaller sub-basal tooth on the inner margin, which is not always present). The figures 
cited give an excellent representation of this species. 
Mr. Kingsley, in his recent Revision of the Gelasimi, 1 refers to this species as 
Gelasimus cultrimanus, Adams and White, but in the specimens designated by White 
Gelasimus cultrimanus, in the collection of the British Museum, the larger chelipede in 
the male is much more elongated, the proximal tooth of the two large triangular teeth of 
the pollex is always wanting, and the distal one is much less prominent and triangulate, 
and these specimens certainly belong to a distinct species or a very distinct and well 
marked variety. It may become necessary, for the reasons urged by Kingsley, to abandon 
the designation Gelasimus vocans for this species altogether. 2 
Adult 
Lines. 
Millims. 
Length of carapace, rather over ..... 
6 
13 
Breadth of carapace, ...... 
9 
19 
, 1 Proc. Acad. Nat. Sci. Philad., p. 140, pi. ix. fig. 7, 1880. 
2 I retain, for the present, the Linnean name for this species, because it is so used by Milne Edwards in his later 
monograph of the group, and by other authors. If, however, the Linnean designation be properly referable to Gelasimus 
tetragonon, or to any other species, it will be necessary to use Dana’s designation, Gelasimus nitidus, for the present 
form, since his figure (tom. cit., pi. xix. fig. 5c) certainly belongs to it. 
