1918.] Stanlfa' Kemp : Decapoda of the Inle Lake. 



83 



The length of the carapace is about four-fifths its greatest breadth, 

 its outline in dorsal view bein,u' much the same as in P. andersonianiim ; 

 it is, however, much deeper, the depth beinti almost or quite three-fifths 

 of the length. The greater depth is, in the main, due to the fact that the 

 u})per surface between the epigastric crests and the posterior margin 

 is decidedly convex, whereas it is Cjuite flat in typical P. andersonianum 

 and almost flat in the var. ramioonense of that species (pi. xxiv, figs. 1, 2). 



The areolation of the upper surface is faint. The mesogastric areola 

 is defined anteriorly by the bifurcation of the frontal groove and post- 

 eriorly by the cervical groove ; its antero-lateral boundaries are al- 

 together invisible. The cervical groove is deeply graven posteriorly 

 and is distinct where it cuts the post-orbital crests, but between these 

 two limits is very broad and shallow. Traces also exist of a groove 

 (very distinct in P. andersonianum) on the epibranchial region, more or 

 less parallel with the cervical groove. The greater part of the upper 

 surface of the carapace is smooth, but in some specimens fine rugae are 

 visible behind the epigastric and post-orbital crests. The epibranchial 

 regions are strongly tuberculous, the tubercles being fewer, larger and 

 sharper than in the related species. The side-walls bear oblique rugae 

 which extend over the postero-lateral border and are visible from above. 



The epigastric and post-orbital crests are similar to those of P. ander- 

 sonianum ; the former are obliquely truncate anteriorly and extend 

 forwards in advance of a line joining the posterior borders of the orbits. 

 The post-orbital crests are straight, undermined and irregularly crenulate. 



The surface of the front is coarsely granular ; its margin, like the 

 upper border of the orbit, is crenulate and in dorsal view is very deeply 



Fig. 1. — Potanion (Potamon) browneunum, sp. nov. 



a. Outline of left side of carapace. 



b. Third maxillipede. 



c. Abdomen of male. 



bilobed. This last character will at once distinguish it from P. ander- 

 sonianum or any of its varieties. The external orbital tooth is sharp 

 and is separated from the serrate lower border of the orbit by a deep 

 notch. 



I 2 



