182 TIIALAMITA POISSONI. 



very rare species , which is so little known yet , that a new 

 description may be allowed. As regards the general phy- 

 siognomy and more especially the shape and the form of 

 the carapace, our species wholly agrees with the Japanese 

 specimens of' Thalamita arcuata de Haau, which is identical 

 \^dth Thalamita sima M. Edw. after Mr. Alph. Milne Edwards. 

 The upper surface is very convex , smooth , somewhat hairy 

 anteriorly and at the lateral parts, minutely punctate, but 

 deflexed towards the front and the lateral parts of the ca- 

 rapace; the median frontal lobes are still somewhat more 

 prominent, being separated from one another by a scarcely 

 visible median incision , the outer lobes are much smaller 

 but straight and directed a little obliquely forward. The 

 anterolateral margins are less arched , directed more 

 straightly backward , though not so much as those of 

 Thai, admete Herbst. The first lateral tooth or external 

 orbital angle, is blunt, as in Thai, arcuata; the second 

 and third teeth are sharp and quite similar, the fourth 

 tooth is always the smallest of all, in one specimen it is 

 rudimentary , in another it is even absent on one side ; 

 the posterior tooth is sharp , directed forward and a little 

 larger than the second or third. The elevated transverse 

 ridges of the iipper surface of the carapace are distinctly 

 developed. The basal joint of the external antennae is pro- 

 vided with a smooth , very depressed crest ; in Thai, arcuata 

 that crest is higher, though also untoothed. The anterior legs 

 are somewhat unequal , either the right or the left leg being 

 the larger. The small hand resembles tolerably that of 7 /mZ. 

 arcuata , but the large hand is higher and of a less slender 

 shape ; the arms are quite smooth , besides the somewhat gra- 

 nular upper margin , the anterior margin is armed Avith three 

 more or less sharp teeth; the carpopodite is armed with 

 an acute tooth at its inner angle , but its upper surface 

 is only provided with some smooth elevated lines termi- 

 nating in blunt prominences. The upper surface of the 

 hands is provided with four spines , which are very sharp 

 in the young specimen , but blunt in the two adult ones , 



Notes from tlie Leytlen Museum , "Vol. II. 



