PISIDIUM. '225 



TYPE, Pisidlum amnicum, Jenyiis, from Europe aucl .Northern 

 Asia. 



llanae. World-wide. 



Shell small, roundly ovate or obliquely wedge-shaped, inequi- 

 lateral ; anterior side longer than the posterior; umbones slightly 

 inflated behind; hinge bearing two cardinal teeth in each valve ; 

 right valve bearing four laterals and the left valve two ; lateral 

 teeth strong ; ligament situated on the smaller (posterior) side ; 

 pallial line entire. 



Animal having the mantle lobes smooth and open ; furnished 

 with a single short (anal) siphon, with non-papillary orifice ; 

 branchial cavity indistinguishable from the pedal cleft ; foot 

 large, tongue - shaped, capable of great extension ; palpes- 

 triangular, elongated. 



367. Pisidium clarkeanum, G. *J- H. yevill. 



Pisidium clarkeanum, G. & II. Nevill, J. A. S. 13. xl, 1871, p. 9, 

 pi. 1, figs. 4, 4 -4 d. 



Original description : Testa ventricosa, pblonga, valide in&qui- 

 lateralis, pallide fulva ; postice elongata ac rotundata, antice 

 rotundate truncata ; umbonibus prominentibus ac tumidis ; super- 

 ficie coneentrice confertim striata, striis tenuibus, regularibus. 



Long. 4*5, lat. 5*5, diam. 8*5 mm. 



Hal. Tanks, etc., close to the Dainuda at Moisraka. 



368. Pisidium hydaspicola, Theobald. 



Pisidium hydaspicola, Theobald, J. A. S. B. xlvii, 1878, p. 147. 



Original description : Testa sub-cordate ovali tenui, exilissime- 

 striata, antice rotundata, postice vix truucata. 

 Long. 3-4. lat. 4, diam. 2-5 mm. 

 Hab. Kashmir, near Shypion. 



Fig. 07. Pisidium hydaspicola, Tlieob. (Tjpe.) x4. 



To the above scanty description is added the following note : 

 " The nearest ally of this species is P. clarkeanum, Xev., but it 

 more rounded in front and hardly truncated behind." 

 The type is in the British Museum. 



