CRUSTACEA OF THE MERGUI ARCHIPELAGO. 209 
punctated, when examined underastrong lense The protogastric 
lobes are quite indistinct. 3 
The front is strongly deflexed and tridentate (the supraocular 
teeth not being included). The median tooth is very small, 
subacute, and being directed perpendicularly downward is 
only partly visible when the carapace is viewed from above. 
The lateral teeth are conical, subacute, much larger than the 
median tooth, and directed forwards and slightly outwards. The 
internal angle of the upper orbital margin (supraocular tooth, 
Miers), which is rounded and obtuse in D. caput-mortuum, is 
rather acute in this species, and its distance from the lateral 
frontal tooth is quite as great as the distance between the 
two lateral frontal teeth. The external orbital angle is obtuse 
and scarcely prominent, and is separated by a narrow hiatus 
from the inferior margin of the orbits, the lobe of which 
is triangular and acute; the inferior orbital lobe of D. caput- 
mortuwm is, on the contrary, very obtuse. The acute internal 
angle of the upper orbital margin is as far distant from the 
lateral frontal tooth as from the obtuse, external, orbital angle. 
The external antenne are a little more than half as long as the 
cephalothorax. 
The antero-lateral margins are as much longer than the 
postero-lateral as in D. caput-mortuum, they are armed, behind the 
external orbital angle, with four small acute teeth of nearly 
equal size. The first antero-lateral tooth is as far distant from the 
obtuse, little prominent, external orbital angle as the latter is 
from the internal angle of the upper orbital margin; the second 
tooth is a little smaller than the first, and its distance from the 
first is a little less than the distance otf the first tooth from the 
external orbitalangle. The third tooth, which is, again, as promi- 
nent as the first, is as far distant from the second as the second 
is from the first * ; the distance of the fourth tooth from the third 
is almost twice as great as the distance between the third and the 
second, and the second tooth is as far distant from the fourth as the 
fourth is from the cervical suture. The fourth toothis as promi- 
nent as the first and the third. A rather acute tooth, in which 
the slightly convex postero-lateral margin terminates, occurs 
* In the small specimen, the cephalothorax of which is only 16 millim. 
long, the second antero-lateral tooth is situated closer to the first than to the 
third. 
LINN. JOURN.—ZOOLOGY, VOL. XXII. 14, 
