CRUSTACEA OF THE MERGUI ARCHIPELAGO. ne 
p- 283, pl. xvii. fig. 8; Alph. Milne-Edwards, Archives du Muséum Hist. 
Nat. 1861, t. x. p. 364, and Nouv. Arch. du Muséum Hist. Nat. 1873, 
t. ix. p. 165, pl. iv. fig. 5. 
One female specimen was collected at Elphinstone Island. 
The distance between the points of the third antero-lateral teeth, 
which we may call the breadth of the carapace, measures 61 millim., 
and the carapace is 89 millim. long. When comparing this 
specimen with the individuals described above as Thal. prymna, I 
observed the following differences :—The frontal lobes are more 
prominent in 7. spinimana, and are separated from one another 
by much longer and broader fissures, and the internal lobes of 
the upper orbital margin are still more arcuated. The median 
frontal lobes are nearly quadrangular, the second tooth is a 
little broader and separated from the median by a fissure which 
appears shorter (less deep) than that by which the two median 
teeth are separated from one another. The third frontal tooth 
extends a little more forward than the others, and is also a little 
narrower ; the outer frontal lobes (the internal lobes of the upper 
orbital margin) are still more arcuate and curved than those of 
Thal. prymna. 
The ridge on the basal joint of the outer antenne is armed 
with three or four black-pointed acute spines, of which the 
two internal are united at their base; they are partially seen 
between the internal arcuate lobes of the upper orbital margin 
and the third frontal tooth. The five antero-lateral teeth of the 
carapace are nearly equal and successively decrease in length, so 
that the fourth tooth is a little shorter than the third, but still 
slightly longer than the fifth. 
The chelipedes are armed with more spines than those of 
Thalamita prymna. The anterior margin of the arms presents 
five spines, of which the proximal and distal ones are, however, 
very small. The wrist bears a strong acute spine at its internal 
angle, and the outer surface is armed with six spines of different 
sizes. The subequal hands are comparatively less high, and 
therefore appear more slender than in Thal. prymna; they are 
armed with eight or nine spines, arranged in two rows on the 
upper margin, and the outer surface presents the same longi- 
tudinal granulated crest which is found in the Mergui specimens 
of T. prymna, but which is absent in individuals from near Djedda 
in the Red Sea, which I propose to refer to Thal. picta. Between 
