iqig.] S. Kkmp : Notes on Cyustacca Decapoda. 345 



and rudimentary, lying in small oblique pits close to the edge of 

 the front and separated by a comparatively broad septum, as 

 in Tympanomerns pusillus and other Scopimerinae. In the 

 Macrophth alminae, to which the genus Cleistostoma belongs, the 

 antennules are well developed, fold quite transversely, and the 

 septum between them is very narrow. These characters constitute, 

 so far as I am aware, the only really valid distinction between the 

 subfamilies Macrophthalminae and Scopimerinae, for the tvmpana 

 found in most species of the latter subfamily are ill-defined and 

 occasionally absent in Tympanomerus. On comparing T. lingula- 

 ius with Alcock's Cleistostoma dotillijonne the differences in the 

 antennules are quite evident. 



The Mergui specimens of T. linguLatus agree very closely with 

 Miss Rathbun's description, but her figure does not altogether 

 succeed in conveying the characteristic appearance of the upper 

 surface of the carapace. In the individuals I have seen the 

 majority of the fine granules are aggregated into small clusters, 

 varying a little in size and arrangement and each set with short 

 dark brown bristles retaining mud. The carapace in specimens 

 which have not been cleaned overmuch is, in consequence, seen 

 to be covered with small furry patches, rather than with isolated 

 granules as in Miss Rathbun's figure. The angle on the lateral 

 margin of the carapace in front of its middle point is in reality 

 more obtuse than in the figure, but it bears a setiferous patch 

 which makes it look more prominent. The oval cavities above 

 the edge of the front are very evident, the species differing in 

 this character from any other known species of Tympanomerus. 

 The prominent median tooth on the epistome is paralleled in T. 

 slevensi and T. fraler. 



The chelipeds of the male are short. The carpus bears a 

 strong tooth on its inner side as in T. gangeticus and T. orientalis ; 

 it is, however, much shorter than 

 in those species, its upper surface 

 being only about one and a half 

 times as long as broad. Above the 

 tooth on the inner side there are 

 some long setae, while on the upper 

 surface there are some short brown 

 bristles. The palm is swollen and 



its height is fully as great as the I'fxi-fig. 18. — 'Fympannmerui^ 



length of the upper border (text-fig. liu^rulatiis (Raihbun). 



18). The outer side is smooth and Chela of male, 



convex ; inferiorly it is rounded, 



without any traces of the longitudinal keels found in many species 

 of the genus. The upper surface is finely granular with scattered 

 setae. On the inner side there is a huge blunt ridge which com- 

 mences near the posterior end of the upper border and curves 

 downwards and forwards to the l^ase of the fixed finger. The 

 summit of the ridge is irregularly tuberculate and, in the area 

 between it and the finger-cleft, there is a patch of long hairs. 



