CRUSTACEA OF THE MERGUI ARCHIPELAGO. 75 
The Leyder Museum contains specimens from the shores of 
Amboina and Timor. 
5L. THatamita sima, I.-Hdw. 
Thalamita sima, Milne-Edwards, Hist. Nat. Crust. t. i. p. 460. 
Portunus (Thalamita) arcuatus, de Haan, Fauna Japonica, Crust. p. 43, 
pl. u. fig. 2, and pl. xin. fig. 1. 
Thalamita sima, Alph. Milne-Edwards, I. ¢. p. 359. 
Two very young individuals were collected at Owen Island. 
They closely resemble the two species of the genus Thalamonyx 
described by Prof. A. Milne-Edwards under the names of Thala- 
monyx Dane and T. gracilipes; but in Thalamita sima the two 
median frontal lobes are less prominent, and the carapace is com- 
paratively more enlarged. I think, however, the genus Thala- 
monyx may ultimately prove to be identical with Thalamita, so 
that it would be better to refer the two foregoing species to 
the latter genus. 
Thalamita sima has been observed on the coasts of Coromandel, 
Java, Amboina, New Caledonia, China, and Japan. Its occurrence 
in the Red Sea is still doubtful, because it is probably represented 
there by the closely allied Thalamita Poissoni, Aud., which I 
have proved to bea distinct species (Notes from the Leyden 
Museum, vol. 11. p. 181). 
52. Tuanamira pryMNa, Herbst. (PI. IV. figs. 5 & 6.) 
Cancer prymna, Herbst, op. eit. pl. lvii. fig. 2. 
Thalamita prymna, Milne-Edwards, Hist. Nat. Crustacés, t. i. p. 461. 
Portunus (Thalamita) prymna, de Haan, Fauna Japonica, Crustacea, 
p- 43, pl. xu. fig. 2. 
Thalamita prymna, Alph. Milne-Edwards, 1. c. p. 360. 
Seven specimens of different size were collected—three at 
Elphinstone Island, one at Owen Island, and three at King 
Island. 
The largest specimen is a male, and its carapace is 53 millim. 
broad; the cephalothorax of an ova-bearing female is only 
30 millim. broad. 
In all these specimens the fourth antero-lateral tooth of the cara- 
pace is rudimentary. They present, however, some differences 
which are probably individual. Thus the upper surface of the 
cephalothorax and of the legs in the specimens from King Island 
is densely covered with short hairs, as in Thalamita Dane ; 
whereas these hairs are nearly wholly absent in the other in- 
