48 ' 



near the distal end, that nearly wholly conceal the next segment; terminal segment slender, 

 tapering. Inner margin of ischium and merus thickly fringed with feathered hairs (fig. 3 a). 



The abdomen of the c? has been well figured by de Haan, but his figure being two 

 small, details are difficult to detect. The first segment is the broadest of all, but very short-, 

 the next is narrower and again shorter; the third and fourth segment retain the same breadth, 

 and the former is longer than the next, that is waved at the anterior margin; the fifth segment 

 is much narrower at the base, it gradually widens distally to nearly the breadth of the second 

 segment and is as long as the preceding segments taken together; the penultimate segment 

 has somewhat convex side margins and is shorter than the preceding; the terminal segment 

 finally is semi-circular. 



The chelipeds are elongate and slender, twice as long as the carapace, but outreached 

 by the anterior pair of walking legs by the length of the dactylus. All the segments are 

 oranular; the meropodite is long and widening distally, sharply-edged above, with some few 

 stiff hairs, but spineless; tympanum at outer surface much smaller than the opposite one ; the 

 wrist is elongate, likewise unarmed, but with a brush of hairs near the proximal end of- the 

 inner margin; the palm is as long as the fingers, low, and rounded at the borders; the fingers 

 are elongate, not gaping, and pointed at tip; outer and inner surfaces of both fingers are 

 marked by a longitudinal row of granules, and the under border of the fixed finger is provided, 

 like the back of the movable finger, with two similar rows; the cutting margins of the fingers 

 are finely crenulate, and in some cases there is a faint prominence, resembling a tooth, in the 

 proximal half of the movable finger. 



Of the walking legs the length gradually diminishes from before backward ; the mero- 

 podites are narrowing distally and unarmed; the dactyli are somewhat curved and as long as 

 the propodites, save in the last pair of legs, where the dactylus is quite straight, even curved 

 backward and distinctly longer than the preceding joint. The hairy-edged pouch leading into 

 the branchial cavity and situated between the first and second pair of walking legs has been 

 already mentioned. Whether such a structure exists also in the other species of this genus is 

 unknovvn to me, as I have, neither with regard to Sc. globosa nor to the other species, found 

 anything in the literature concerning this. 



Tympanomerus Rathbun. 



1S35. Cleistostoma (part.) de Haan. Fauna Japon., Crust., p. 26. 



1888. Dioxippe de Man. Journ. Linn. Soc. London, v. 22, p. 137 (praeocc). 



1897. Tympanomerus Rathbun. Proc. Biol. Soc. Washington, v. 11, p. 164. 



The genus, of which "-Cleistostoma" pusilla de Haan is the type, comprises some small 

 crabs, which, though sometimes resembling Dotilla and the like by the presence of tympana 

 on the legs, in their general appearance approach Macropthalmus, for the body is less cubical 

 than in Dotilla and the carapace is decidedly broader than long. By the shape of the abdomen 

 of the cf and of the external maxillipeds they are decidedly related to Scopimera, but the ischium 

 of the external maxillipeds is shorter than the merus. The cf sex especially is remarkable by 

 the bulky size of the chelipeds, that are much stouter than the ambulatory legs. 



4 S 



