32 



Group II. : anthrsonianum group. 



In this crroup, which inchides P. andersonianum and its varieties, P. 

 rangoonense, P. edrvardsi, P. Iiirtum, and P. hispidwn, the cervical groove 

 follows the same course, and cuts the post-orbital crests at much the same 

 point, as in Group I., but the merus of the external maxillipeds is as long as, 

 or longer than, broad. 



The species may be tabulated as follows : — 



I. Post-orbital crests salient and undermined as usual, and cut by the cervical 

 o-roove at a point in line with the inner limit of the outer orbital spine : — 

 i. Carpus of chelipeds dorsally umbilicated and with the anterior 

 border a little tumid ; carajjace and legs not hirsute : — 



1. Edge of front sinuous, faintly bilobed .... V.andcisomanum. 



2. Edge of front sinuous, faintly four-lobed ; chelipeds particularly 



joutrh . . . . . . ■ -P. raiigooiieitse. 



ii. Carpus of chelipeds dorsally umbilicated and with the anterior border 

 very much swollen ; large pustule-like tubercles on dorsum of palm 

 of hand : — 



1. Carapace sparsely setose ; legs not hirsute . . .P. ednanhi. 



2. Carapace and legs strongly hirsute . . . .P. hirltim. 

 II. Post-orbital crests blunt, depressed, not undermined, and cut by the cervical 



groove at a point in line with the outer limit of the outer orbital spine ; 



carapace hirsute posteriorly, legs strongly hirsute . . .P. hispidum. 



10. PoTAMON (Potamon) ANDERSONIANUM, Wood-Mason. (Fig. 40.) 



Telphnsa andersoniana,VfooArMa.s,oa, iourna.\ Asiatic Soc, Bengal, XL., Part II., 1S71, p. 451, pi. xxvii.. 

 figs. 16-20. 



Potamim{Polnmon)andersiinianus. M. J. Rathbun, Nouv. Archiv. du Museum, Paris (4), VI., 1904, p. 274 

 (uhi lit.). 



This species is distinguished from all the preceding by the form of the 

 merus of the external maxillipeds, which, instead of being broader than long 

 and pentagonal with the antero-external angle rounded, is slightly longer than 

 broad and irregularly hexagonal. 



From P. Jiuviatile and its varieties it further differs in the following 

 particulars : — 



(1) The cervical groove is broadly and deeply cut in all its extent ; 



(2) The gastric and epibranchial regions are distinctly areolated, and the 

 surface sculptm'e of carapace and chelipeds is bolder ; 



(3) The front is narrower, its breadth in the adult being much less than 

 one-third the greatest breadth of the carapace ; 



(4) The external orbital and lateral epibranchial spines are less salient ; 



(5) The epigastric and post-orbital crests, though distinctly separated, 

 form one curve, the trend of which is very slightly convex forwards. 



From P. atkinsonianum, P. koolooense, and their varieties, it differs in the 

 following characters, besides that mentioned at the outset :— 



