29 



6. POTAMON (PoTAMON) ATKINSONIANUM, var. VENTRIOSUM. 



An adult male in the collection must be more particularly noticed. It 

 agrees in every respect with what I take to be Wood-Mason's type of the 

 species, except in the form of the abdomen. The whole abdomen is broader, 

 its 6th segment is twice as broad as long, and its 7th segment is a good deal 

 broader than long. The specimen is a well-formed male with carapace 1::; inch 

 long and 1^ inch broad. 



-jTT- Near Sanesvar, Kumaon, about GOOO feet. L. L. Feritior. 1 <?. 



This " variety " may possibly be only an individual abnormality. I mention 

 it, however, as in grouping the species I have laid stress on the form of the 

 abdomen (and the correlated form of the mandibular palp). The abdomen is 

 usually broader in young males than in adult males in the genus Potamon, but 

 this is undoubtedly an adult. 



7. Potamon (Potamon) atkinsonianum, var. emphyseteum. (Fig. 2.) 



This variety, though of peculiar form of carapace, owing to the very strong 

 convexity of the antero-lateral and concomitant strong convergence of the 

 postero-lateral borders, can not be specifically distinguished. 



It agrees with what I take to be Wood-Mason's type in all particulars 

 except the following :■ — 



(1) The antero-lateral borders of the carapace form a very strongly- 

 convex curve and the postero-lateral borders are in consequence strongly 

 convei'gent ; the bulge of these epibranchial borders adds so much to the 

 breadth of the carapace, that in some specimens it is more than three and 

 a half times the width of the front. Other results of this lateral bulging 

 are — (a) that the rugse of the anterior part of the epibranchial regions are 

 nmch more oblique ; and (b) that the gap between the epigastric and post- 

 orbital crests is widei', and this makes the epigastric crests appear more 

 prominent. 



(2) The length of the 6th abdominal segment of the adult male is always 

 two-thirds its greatest breadth, whereas in a series of typical atkinsonianum it 

 is a variable amount less than two-thirds. 



In the largest male the carapace is 11 inch long and 21 inches broad. 



6991 



— ^^. Bilaspur, Punjab. A. Rahman. 4 $ , 9. 



o 



^. Kangra, Punjab. F.Day. 1(?,1$. 



Two other young males may be referred to this variety, the lateral puffing 



