ei 
CRUSTACEA OF THE MERGUI ARCHIPELAGO. 171 
The anterior legs are also nearly alike in both species, but 
the prominences of the upper margin of the mobile finger have 
a characteristic form distinctive in each. Inthe male of S. aspera, 
the upper margin of the mobile finger presents a row of 16 or 17 
transverse oval tubercles, each of which is symmetrical with regard 
to a median, transverse, smooth ridge, the tubercles resembling a 
Chiton, as in S. bidens,de Haan. In 8. Melissa the upper margin 
of the mobile finger presents a row of 14-15 prominences, which 
are also transverse, but are not symmetrical and do not resemble 
a Chiton. The anterior (distal) declivity of each tubercle is 
larger than the posterior (proximal) declivity, and the former 
is distinctly excavated, the prominences being somewhat horse- 
shoe-shaped. In other particulars, the hands are perfectly similar 
in the two species ; and in each the anterior margin of the arm 
presents an acute spine, and its upper margin terminates also in 
a small acute tooth. 
The meropodites have the same form, being equally enlarged 
in both species. The carpopodites and propodites are, however, a 
little more slender in S. Melissa than in S. aspera, and the dactylo- 
podites are a little shorter in proportion to the length of the 
propodites. 
The upper surface of the cephalothorax is ornamented with 
violet markings, and the propodites of the ambulatory legs with 
two violet rings, parallel to one another. 
Dimensions :— 
millim 
Distance between the external orbital angles .... 15 
imength of the cephalothorax .. 3... 252-1 1.0. 123 
IBTEACbM On GMO OMG, —<igers ccc. a. si a de Weve eae 82 
Sesarma Melissa stands in the same relation to Sesarma aspera 
as Sesarma Haswelli to Sesarma bidens. 
94. SzsarMa Prcta, de Haan. 
Grapsus (Pachysoma) pictus, de Haan, Fauna Japon. Crust. p. 61, 
Taf. xvi. fig. 6. 
Sesarma picta, Milne-Edwards, Ann. Sci. Nat. 3° série, t. xx. p- 184; 
de Man, Notes from the Leyden Museum, vol. ii. p. 22. 
The collection contains one young female specimen, found in 
fresh water on Sullivan Island. 
The distance between the external orbital angles measures 
123 millim., the front between the eyes 64 millim., and the 
cephalothorax is 10 millim. long. | 
