CRUSTACEA OF THE MERGUI ARCHIPELAGO. 177 
margin ; this character is presented also by S. bedens and SN. gut- 
tata, but never by S. Dussumiert. In both species the inner 
surface of the hands is only faintly granular. The joints of the 
4 
male abdomen are quite similar in S. Haswell and S. bidens; the 
figure of the latter in the ‘Fauna Japonica’ may therefore be 
consulted. 
Dimensions of the larger specimen :— 
millim. 
Distance between the extraorbital teeth ........ 174 
ength of the cephalothorax 7... 2.2.1.1 2 sees 132 
Sesarma Haswelli occurs also at Ceylon, and I have little 
doubt that the specimen recorded by Hilgendorf from that 
locality belongs to S. Haswelli (Crustaceen von Ost-Africa, 
p. 91, in V. d. Decken’s Reisen). 
I now add for comparison the distinctive characters of S. 
guttata, which inhabits the eastern coast of Africa. This species 
is also most closely allied to S. b¢dens, but the tubercles of the 
upper margin of the mobile finger are larger and more prominent, 
and the penultimate joint of the male abdomen is comparatively 
much longer, the proportion of the breadth of its posterior margin 
to the length being in S. guttata as 7 : 5, and in NS, bidens as 7: 33. 
The prominent tooth near the distal end of the anterior margin 
of the arm, which in NS. didens is very acute, simple, and spiniform, 
is represented in S. guttata by an acute dentiform prominence, 
which is itself a little denticulate. The second antero-lateral 
teeth of the cephalothorax are somewhat more prominent in S. 
guttata. In other respects these two forms closely resemble 
one another. 
97. Sesarma Dussumirei, W-Hdw. (Pl. XII. figs. 8-12.) 
Sesarma Dussumieri, Milne-Edwards, Annales des Sciences Naturelles, 
t. xx. 1853, p. 185. 
One fine male specimen was collected at Tavoy. 
Sesarma Dussumieri was unsatisfactorily characterized by the 
late H. Milne-Edwards, and it has therefore never been recog- 
nized by subsequent authors. It differs more from 8S. bidens 
than from Sesarma Haswelli and S. guttata. Except in the 
abdomen of the male, the joints of which have a different 
form, the cephalothorax of Sesarma Dussumiert resembles that 
of Sesarma bidens. The third joint of the male abdomen, 
which is the broadest of all, is comparatively shorter in S. Dussu- 
LINN, JOURBN.— ZOOLOGY, VOL. XXII. 12 
