Goree Island, Senegambia. 277 
distal ends fringed with long hairs; the penultimate and 
antepenultimate joints are somewhat dilated near the distal 
ends of their inferior margins ; the terminal joints are slender. 
The chelipedes are very unequal, the right being small and 
the left considerably enlarged ; in the right the wrist is about 
as long as the palm, and both are externally granulated and 
hairy, the hairs being more dense on the hands; fingers a 
little longer than the palms, scarcely denticulated on their 
inner margins, and subexcavated towards the tips, which are 
corneous and black. The left chelipede has the arm very 
short, thick, trigonous, with a strong blunt tubercle on its 
under surface ; wrist and hand naked, the wrist shorter than 
the palm, and externally closely granulated; palm shorter 
than its vertical depth, somewhat compressed, with the outer 
surface covered with large flattened granules. A longitudinal 
series of more prominent granules exists near the upper 
margin, and a longitudinal series of larger, transversely set, 
flattened tubercles parallel to the lower margin, which is 
sharp-edged and crenulated ; fingers very short, granulated 
externally, acute at the apices; the mobile finger with the 
outer surface deeply concave. Second and third legs robust ; 
the right legs of each pair have the joints nearly smooth ; 
dactyli a little longer than the penultimate joints, with black 
corneous tips: the third leg on the left side has the upper and 
outer margins of the last two joints carinated, and the outer 
surface concave, the concavity being deepest on the last joint. 
In the fourth legs (which are shorter and more robust than 
the fifth) the small dactylus impinges against the produced 
scabrous portion of the preceding jomt; the slender fifth legs 
are not chelate; the male postabdomen is armed with four 
filamentous appendages on the left side, besides the uropods, 
which are very unequally developed, the left being much the 
larger. Colour (in spirit) yellowish, inclining to orange on 
the front of the carapace, eye-peduncles, and legs; left cheli- 
pede of a slaty or purplish tinge. Length of the carapace of 
the largest specimen (a male) about 10 lines (21 millim.). 
The legs are not capable of complete extension. 
The form and sculpture of the left chelipede apparently 
distinguishes this species from all its congeners. 
Isocheles ? gracilis, sp.n. (Pl. XVI. fig. 4.) 
Tn this species the carapace is membranaceous, widest pos- 
teriorly (at the back of the branchial regions), with the sides 
nearly straight and convergent thence to the front, which is 
sinuated, but without any rostriform projection; so that the 
