CRUSTACEA OF THE MERGUI ARCHIPELAGO. 141 
its outer surface is smooth, and presents an arcuate piliferous 
line, proceeding from the middle of the external margin towards 
the internal half of the anterior margin. The latter, which 
forms the commissure between the merus-joint and the ischium- 
joint, is transverse (not oblique, as in Scopimera globosa and 
S. tuberculata) and straight, though a little concave towards the 
internal angle, which projects slightly more forward than the acute 
external angle. The internal and external margins of the ischium- 
joint are also slightly concave. The merus-jointisa little longer 
than the ischium-joint, and presents the same form asin the genus 
Dotilla (sensu stricto). The external and internal margins are 
arcuate, convex, and convergent anteriorly, so that the anterior 
margin of the joint is very short ; this anterior margin is slightly 
concave, and bears the palpus near the external angle. Except 
a narrow, shallow, longitudinal impression which proceeds close 
and parallel to the external margin, the outer surface of this joint 
appears quite smooth, and without any trace of the grooves that 
characterize the species of Dotilla. 
The male abdomen is narrow, and is similar to that of some 
other species of this group, the fifth (or antepenultimate) joint 
being much constricted near its base. The very short first seg- 
ment occupies a little more than half the width of the sternum 
between the bases of the last pair of legs; the second segment 
is a little less broad, but slightly longer; the third segment is 
the broadest of all, being a little broader than the first, 
slightly longer than the first two joints taken together, and its 
lateral margins are arcuate; the fourth is as long as the third, 
but a little less enlarged; the fifth joint is about once and 
a third longer than the fourth, and a little narrower, and pre- 
sents a characteristic constriction near the base; the sixth or 
penultimate joint is a little longer and broader than the fifth, 
and almost quadrate ; while the terminal joint is as long as the 
fifth, and rounded at the tip. The lateral margins of the abdo- 
men are fringed with short hairs; its outer surface, like that of 
the sternum, is quite smooth and glabrous. The female abdomen 
presents the ordinary form. 
The anterior legs of the male are equal or sometimes rather 
unequal. They are similar to those of Helecius; but the fingers 
have acute tips. The chelipedes are large and long, measuring 
about three times the greatest width of the cephalothorax. 
The basipodites and ischiopodites are smooth and unarmed. 
