262 
THE VOYAGE OF H.M.S. CHALLENGER. 
is much enlarged, with the antero-external angle much produced and rounded ; the next 
joint is articulated at or near the middle of the distal margin of the merus. The 
chelipedes (in the male) are often considerably developed; the merus is trigonous; carpus 
without a spine on its interior margin ; palm sometimes compressed but not flattened or 
concave, on the exterior surface, and usually with a lanate patch of hair on the exterior 
surface at the base of the fingers, which are distally acute or subacute. Ambulatory legs 
with the joints not dilated; dactyli styliform, without marginal spines. 
Thus characterised the genus Pseudograpsus is nearly allied to Varuna (see below), 
and to a genus represented by two or three species in the collection of the British 
(Natural History) Museum, which I identify, somewhat doubtfully, with Ptychognathus, 
Stimpson ( Gnathograpsus , A. Milne Edwards), and which is distinguished from Pseudo- 
grapsus by the flatter carapace, with nearly horizontal front, and without distinct 
epigrastic lobes, and the enormous development of the exognathi of the exterior maxilli- 
pedes. Another genus, represented by a single species from the Fiji Islands and New 
Hebrides in the collection of the museum, which I will designate Macrograpsus, is 
characterised by the form of the palms and dactyli of the chelipedes in the male, -which 
are greatly dilated and flattened on their exterior surfaces. The species may be desig- 
nated Macrograpsus orientalis. The species of Pseudograpsus have been enumerated by 
Mr. Kingsley. 1 
The genera Cselochirus, Nauck, and Pachystomum, Nauck (Zeitschr. f. wiss. Zool., 
vol. xxxiv. pp. 66, 67, 1880), based on types from the Philippines, and which are allied to 
Pseudograpsus, are too briefly described for certain identification with any of the 
above-mentioned genera. 
Pseudograpsus albus, Stimpson. 
Pseudograpsus albus, Stimpson, Proc. Acad. Nat. Sci. Philad., p. 104, 1858. 
„ „ A. Milne Edwards, Nouv. Arcliiv. Mus. Hist. Nat., vol. ix. p. 314, 
pi. xviii. fig. 2, 1873. 
,, „ Kingsley, tom. cit., p. 205, 1880. 
Kandavu, Fiji Islands, July 1874. (Two males). 
In the specimens I refer to this species, the front curves slightly downwards, and the 
epigastric lobes are distinctly defined. The antero-lateral margins also are slightly arcuated. 
. Lines. Millims. 
Length, of carapace, nearly ...... 4^ 9 
Breadth of carapace, nearly . . . . . . 5 10 
These characters are perhaps the best that can be cited to distinguish this genus 
from Ptychognathus, Stimpson ( Gnathograpsus , A. Milne Edwards), since in the 
1 Gnathograpsus pilipes, A. Milne Edwards, is, for reasons I have indicated below, to be referred, I think, to the 
genus Pseudograpsus. 
