19 1 3-] StanIvEy Kemp : Crustacea Decapoda. 299 



Feb. 1st, IQ12. Three specimens, i & and 2 $ , with sym- 

 biotic TemnocephaHdae, from a small stream flowing into the Siyom 

 R. below Debuk Damda C^). 



Feb. 5th to roth, 19 12. Five specimens, 3 cf and 2 2 , from 

 a stream between Renging and Upper Renging, collected by'Capt. 

 de Courcy and Mr. I. Burn Murdoch C"^). 



Var. lophocarpus, nov. 

 (Plate xviii, figs. 13, 14.) 



Thirty-five additional specimens of P. adiatretum are distin- 

 guished from the preceding by characters of sufficient importance 

 to merit varietal recognition. 



In general facies these examples bear an exceedingly close 

 resemblance to the others. The form of the carapace is identical 

 and differs in the features already noted from the type of P. adiatre- 

 tum. Examined with a lens, the same pitting is observed, but the 

 surface is dull and does not present the polished appearance whicli 

 characterizes the majority of the typical specimens. 



It is, however, in the structure of the chelipedes that the most 

 distinctive varietal differences are to be found. In the var, lopho- 

 carpus no trace whatever remains of the spine at the inner angle 

 of the carpus (fig. 14) and, were it not that this spine is reduced 

 in size in the Abor examples of P. adiatretum (fig. 12) this charac- 

 ter alone might be held sufficient for specific differentiation. 



In the variety also a tuft of coarse hairs, entirely absent in 

 the case of the other specimens, springs from the antero-internal 

 face of the carpus, i.e. the portion on which the palm of the chela 

 abuts when the limb is flexed. In addition, short hairs of a simi- 

 lar nature are to be found round the base of the dactylus and at 

 the proximal end of the inner margins of both fingers (fig. 13). 

 These hairs are scanty or, in rare instances, wholly missing in some 

 of the largest individuals, but it may, I think, be assumed that 

 their absence in these cases is due solely to mechanical agencies. 



The eggs of an ovigerous female were in fife of a bright red 

 colour. 



To specialized local races in which the geographical factor 

 can be successfully demonstrated the term ' sub-species ' is perhaps 

 more properly applicable; but as the term ' variety' has frequently 

 been used with a geographical significance in the case of fresh- 

 water crabs, it should be noted that all the evidence available with 

 reference to the var. lophocarpus negatives the view that it is a 

 localized race. Although the two forms of the species were not 

 actually found together, the localities in which one or other occur- 

 red have no precise correlation with either horizontal or vertical 

 distribution : the variety was found at a place exactly inter- 

 mediate between others in which only the typical form was taken. 

 The specimens were found in hill streams at an elevation of 

 600-2000 ft. above sea-level. 



