180 DR J. G. DK MAN ON THE PODOPHTHALMOUS 
closely that of the other species, that it is scarcely possible to 
distinguish between them. The principal caaracters by which 
it differs from the other species are found in the anterior legs 
and more especially in the hands. 
In S. livida the fingers are comparatively shorter in propor- 
tion to the palm, the latter being more developed. The pro- 
portion of the horizontal length of the fingers to that of the 
palm, measured at the lower margin, is in S. livida as 10: 11, 
in S. guttata as 10:93, in S. Haswelli as 10 : 9, in S. bidens 
and in S. Dussumiert as 10: 8. In Sesarma livida the im- 
mobile finger is thus shorter than the length of the lower margin 
of the palm; in the four other species the latter is shorter than 
the immobile finger. 
The anterior margin of the arm presents a strong, simple, 
acute, and triangular tooth ; and the upper margin of the immobile 
finger is covered with a longitudinal row of 10-11 low and some- 
what scalariform prominences. As regards the form of the male 
abdomen, S. livida completely agrees with S. bidens. 
The Mergui specimens agree very well, in the form of the 
cephalothorax and the shape of the male abdomen, with the 
adult typical specimen of S. /ivida in the Paris Museum. The 
legs, however, are slightly different. Thus the spine of the 
anterior margin of the arm has a somewhat different form from 
the New-Caledonian type, in which the anterior (distal) margin 
of the spine makes a rather obtuse angle with the distal part of 
the anterior margin of the arm, lying beyond the spine, whereas 
in the Mergui examples the angle so formed is nearly a right 
angle, as in S. bédens. The fingers are shorter than the palm, the © 
above-defined proportion being as 10: 12. The upper margin of 
the mobile finger presents ouly seven slightly prominent eleva- 
tions, which seem to have a different structure from those of the 
New-Caledonian type specimen. ‘The outer surface of the im- 
mobile finger is also a little more flattened than in the latter, 
and the meropodites of the ambulatory legs are somewhat 
more enlarged. Perhaps a careful examination of adult specimens 
of the Mergui species will prove it to be distinct from the 
New-Caledonian Sesarma livida. 
Dimensions of the largest specimen : — 
millim. 
Distance between the extraorbital teeth ee 5%. 162 
Length of the cephalothorax”. .. 7...) S72 eee 13 
