new Commensal Prawn. 133 
again as stalk, outer flagellum very slightly longer than 
inner, its thickened part rather more than a third of its whole 
length, cleft less than halfway ; antennal scale broad, con- 
siderably outreaching antennular stalk, rather acutely pointed, 
with the spine of the outer edge set back about a quarter of 
the length from the end, antennal stalk reaching end of first 
joint of antennular ; second and third maxillipeds without 
exopodites ; third maxillipeds moderately slender, reaching a 
little beyond origin of antennal scale; legs of first pair 
a little outreaching antennal scale, with wrist very slightly 
shorter than hand, and fingers straight, simple, sharp-edged, 
and sharp-pointed, bearing a few bristles at the end ; legs of 
second pair unequal, the larger reaching nearly as far as the 
antennular flagella, with long, almost rectangular palm, a 
little swollen towards the base, simple fingers, not quite half 
length of palm, bearing a few hairs at the tips, wrist simple, 
unarmed, about half length of fingers, arm simple, unarmed, 
about three-quarters length of palm; walking-legs stout, sub- 
equal, the first pair reaching nearly to the end of the first 
chelipeds, unarmed save for a movable spine near end of 
each propodite and some stout bristles, with a swelling on the 
underside of the meropodite near its distal end, and a slight 
projection of the base of the dactylopodite, which is short, 
stout, and rather strongly hooked; sixth abdominal segment 
longer than fourth and fifth together, about as long as telson ; 
endopodites of uropods a little longer than telson, shorter than 
exopodites ; telson tapering, truncate, with the intermediate 
pair of terminal spines very strong. 
Colour in life “almost transparent except the ovigerous 
females, which are pigmented according to the gorgonian on 
which they live, orange, lemon-yellow, or almost red.” 
Length ‘5--7 mm. 
‘l'ype-specimens in the U.S. National Museum. 
The affinities of the species are not very clear. Its 
simplicity of form and the almost complete absence of spines 
from its rostrum, trunk, and limbs seem to point to a rela- 
tionship with P. aurantiacus (Dana), 1852, and, if this 
suspicion be confirmed, we have in P. beaufortensis a second 
member of the subgenus Ensiger; but until more is known 
about P. awrantiacus nothing can be said with confidence upon 
the subject. 
