CRUSTACEA OF THE MERGUI ARCHIPELAGO. 173 
emarginate in the middle, and is perfectly smooth. The four 
subequal postfrontal lobes are little prominent, so that they do 
not conceal the anterior margin of the front, when the carapace 
is looked at from above. The upper orbital margin is very 
oblique. The straight lateral margins of the upper surface of 
the carapace are nearly parallel, scarcely converging backwards ; 
behind their lateral tooth (the acute external orbital angle) 
they present a trace of a second tooth. The foremost of the 
oblique elevated lines with which the sides of the upper surface 
are provided projects a little externally beyond the lateral 
margin, and sometimes even the next oblique line projects a little 
beyond the lateral margin, though not so much as the foremost, 
and in these specimens a trace even of a third tooth is 
observed. 
As regards the under surface of the cephalothorax, I have 
little to remark. The male abdomen has about the same form as 
in S. guadrata, Fabr. (=ungulata, M.-Edw.,=affinis, de Haan), 
the penultimate joint appearing rather short in proportion to its 
breadth. The last joint of the female abdomen is pushed deeply 
into the penultimate. 
In the adult male the anterior legs are of unequal size. The 
ischiopodite of the anterior legs is armed anteriorly with a 
small acute tubercle. ‘The acute upper margin of the arm 
is entire; its distal end is rounded and does not terminate in 
an acute spine. The anterior margin is dilated distally into a 
triangular crest, which appears minutely denticulate anteriorly, 
but is never armed with a spine. The acute under margin 
is also almost entire. The outer surface of the arm is trans- 
versely rugose, but the anterior and the inner surfaces are 
almost perfectly smooth, the triangular crest of the anterior 
margin presenting only some rugose lines on its inner surface, 
and is separated from the rest of the inner surface of the arm by 
the ordinary marginal row of hairs. 
The upper surface of the carpopodite is covered with many 
minutely granular, transverse lines, and the inner angle is not 
armed with a tooth; the inner margin presents a few short hairs 
near the articulation with the arm. The convex outer surface 
of the palm is almost smooth, being, however, minutely rugose 
towards the upper margin and close to the articulation with the 
wrist, and minutely punctate near the articulation with the 
mobile finger. The rounded under margin presents some deli- 
