158 
THE VOYAGE OF H.M.S. CHALLENGER. 
dentiform. The orbit has two very obscurely indicated sutures in its upper margins ; its 
lower margin is subentire, without distinct spinules. The antero-lateral margins are 
shorter than the postero-lateral, and are armed with three spiniform teeth ; there is no 
distinct tooth or spine at the outer angle of the orbit, and the small tooth which in this 
genus usually exists on the subhepatic region is also deficient, but the subhepatic region 
is granulated. The terminal segment of the male post-abdomen narrows somewhat to 
the distal extremity, which is bluntly rounded. The eye-peduncles are of the form 
usual in the genus, moderately short and thick. The antennae terminate in rather long 
flagella, their basal joint barely reaches to the subfrontal process, and does not nearly 
attain the inner suborbital angle ; the merus-joint of the outer maxillipedes is rather 
broader than long, and is distinctly excavated at its antero-internal angle. The 
chelipedes are nearly of equal size, but the right is a little larger than the left ; the 
trigonous arm or merus-joint has a strong curved spine near the distal end of its upper 
margin, the wrist is covered on its upper and outer surface with large but not very 
numerous granules, which in some places are spinuliform, and there is a spine on the 
inner margin of the wrist ; the palm, also, is covered on its upper and outer surface with 
conical acute granules, which on the upper margin are more distinctly spinuliform, and 
are disposed in longitudinal series over the whole of the outer surface, but on the lower 
margin are more numerous and crowded ; the fingers are short, armed on their inner 
margins with rather indistinct serrated teeth ; the dactylus longitudinally sulcated and 
granulated at the base. The ambulatory legs are rather robust and of moderate length ; 
the merus-joints in the first three pairs are armed with a blunt tooth or lobe behind the 
upper and distal angle, which is also produced, dentiform and acute ; the dactyli are 
styliform, more slender than the preceding joints, and armed with a small claw. The ground 
colour of the carapace and limbs (in spirit) is light reddish-brown, but the pubescence 
with which the body and legs are clothed is of a whitish-yellow hue ; the fingers are 
chocolate-brown ; the coloration not extending over any part of the inner and outer 
surface of the palm. 
Adult g. Lines. Millims. 
Length of carapace, . . . . . . . .7 15 
Breadth of carapace, about . . . . . . .9 19 
Length of larger chelipede, when extended as far as its conformation will allow, 9 19 
Length of second ambulatory leg, about ...... 1 inch 25 
The single specimen in the Challenger collection (an adult male), was collected off 
Nukalofa, Tongatabu, in 18 fathoms (Station 172). 
I have examined in the British Museum collection a specimen apparently of this 
species, without definite locality, referred to above as having been erroneously designated 
Pilumnus scabriusculus, White. The pubescence is everywhere much thinner than in the 
Challenger specimen, and is, in fact, nearly absent from the dorsal surface of the carapace. 
