» 



48 



Chelipeds a little unequal, their outer surface rugulose, inclining to be 

 granulous along the inner border of the carpus and upper border of the palm ; 

 edges of merus crenulate ; the usual bicuspid spine is present at the inner 

 angle of the carpus ; the fingers gape slightly when closed, and there are some 

 granules at the base of the upper border of the dactylus. 



Legs about as long as chelipeds ; in the 2nd and 3rd pairs the propodite is 

 more than twice as long as broad. 



In the single specimen, a male, the carapace is IJ inch long, 2 inches 

 broad, and not quite Hhs inch deep. 



Distribution : Siam, Cochin China. 



'- '-. Bangkok. J. Wood-Mason. 1 <S . 



7 " 



This species does not belong to the fauna of British India, but I include a 

 description of it in this memoir for several reasons of practical utility, and also 

 because by other authors it has been reckoned as Indian. 



25. PoTAMON (Potamon) manii, Eathbun. (Fig. 46.) 



Potamon {P(Aamiju) manii, M. J. Rathbun, Nouv. Archiv. du Museum, Paris (4), VI., 1904, p. '21 6 {tibi syn.), 

 pi. xi., fig. 6. 



This species is very like P. larnaudii, and Dr de Man, who originally 

 described it, regarded it as a variety of that species. 



The following are the differences compared with P. larnaudii: — The 

 carapace is distinctly broader (adults being compared), owing to the stronger 

 curve of the antero-lateral borders. 



The cervical groove is similar in that it — («) is deep and narrow where it 

 limits the mesogastric lobule ; and (h) broadens out remarkably beyond this 

 point ; and (c) does not cut the post-orbital crest ; but the expanded part of the 

 groove is deeper, and beyond the expansion the groove is well graven almost up 

 to the lateral epibranchial spine. The comparative difference is well shown in 

 Miss Eathbun's figures. 



The anterior part of the mesogastric areola is even narrower. 



The sides of the front are less oblique and make a more pronounced angle 

 with the free edge ; the edge, again, is more sinuous, and is often, in fact, quite 

 distinctly four-lobed. 



The post-orbital crest usually runs clear and sharp into the lateral 

 epibranchial tooth, without breaking into tubercles. 



The merus of the external maxillipeds is broader than long. 



The legs are decidedly shorter than the chelipeds ; in the 2nd and 3rd pairs 

 the propodite is only twice as broad as long. 



The fingers of the chelipeds are stouter. 



The 7th alidominal segment of the male is as long as broad. 



