PABREYSIA. 159 



The anterior and posterior cicatrices are distinct, the apical 

 ones disposed on the underside of the cardinal tooth. 



Taken by the author of the species at Bhitoura, between Cawn- 

 pore and Allahabad and represented by specimens in the Indian 

 Museum Collection from the following localities : Moradabad; 

 River Indus; Barrack River; Silcher; Rajputana ; Berhampur; 

 Dacca ; E. Cachar ; Sylhet ; Tezpore ; Poona ; Karnul, Madras ; 

 Calcutta (J. Wood- Mason}; Arrah ; Rajmahal ; Hazrapur; Rani- 

 gunga; Sunderbunds. 



An enormously variable species, of which many varieties have 

 been described, several of these appear, however, to be somewhat 

 obscure; the original descriptions are nevertheless given below: 



Yar. marcens (Benson), A. M. N. H. x, 1862, p. 188. 

 Unio marcens, H. & T., 0. I. 1876, p. 19, pi. 42, figs. 4-6. 



Original description : Banded with olive and green ; nacre 

 salmon-coloured ; beaks nearly smooth, eroded ; sulci obsolete ; 

 lunule narrow. 



Long. 44, lat. 66, diam. 27 mm. 



Hal. Berhampooter River, Assam. 



Var. trigona (Benson). 



Unio favidens, var. densa, A. M. N. H. x, 1862, p. 188. 



Original description: Shell with a piceous epidermis, more 

 oblique ; beaks and nacre as in type ; lunule broad. It shows an 

 inclination to verge towards U. triembolus. 



Long. 44, lat. 67, diam. 27 mm. 



Hab. Nujeebabad, in the North-west of Rohilknnd. 



Yar. densa (Benson). 



Unio favidens, var. densa, A. M. N. H. x, 1862, p. 189. 



Original desertion : More solid and tumid [than the typical 

 form] ; epidermis yellow-brown, eroded ; lunule as in type ; shell 

 more oblique. 



Long. 33, lat. 47, diam. 24 mm. 



Hab. Ganges River, above Chunar, between Allahabad and 

 Benares. 



Yar. deltae (Benson). 



Unio favidens, var. delta, A. M. N.H. x, 1862, p. 189; H. & T., 

 C. I. 1876, p. 19, pi. 42, %. 2. 



Original description : Epidermis olive-green and yellow, rayed ; 

 nacre salmon-coloured ; rugae on umbones very distinct, some also 

 on the upper part of the umbonal hinder slope ; lunule somewhat 

 broader than in the type ; cardinal teeth narrower. 



Long. 34, lat. 47, diara. 24 mm. 



