— 101 - 



Planorhis infraliratus nov. sp. 



Testa discolor, supra rufescenti-cornea, infra albida, firma' 

 solida, nitida, supra in centro immersa, subtus latius 

 umbilicata, supra sublaevigata vel sub lente creberrirae 

 striatula, infra striis densissimis transversis ornata, liris 

 obsoletis vel lineis elevatis 4 parallelis spiralibus mu- 

 nita ; anfr. 4 , celeriter accrescentes, sutura sat pro- 

 funda disjuncti , ultimus latus , supra convexus, pone 

 suturam obtuse angulatus, peripheria rotundatus, infra 

 planiusculus ; apertura perobliqua, lunato-ovata, peri- 

 stomate simplici, acuto, raarginibus longe distantibus, 

 callo tenui albo junctis, exteriore longe provecto. Diam. 

 maj. 4^/3, min. 0^/3, alt. 1^/3 mm. 



Hah. in Sibiria prope Jenissei ad Nischnij Inbaltsk (lat. 

 630 50'). 



Valvata sibirica Midd. restit. Westerl. 



Testa discoidea, supra omnino plana, subtus late umbili- 

 cata, virescenti-eornea, transversim dense sublamellato- 

 striata, argenteo-micans; anfr. S^/g, forte accrescentes, 

 cylindracei , ultimus magnus , aperturam versus dila- 

 tatus et ampliatus; apertura magna, circularis, peristo- 

 mate undique recto, continuo, margine superiore quam 

 anfr. penult. humiliore. Diam. maj. 5, min. 3^/^, apert. 

 2 mm. longa et lata. 



Valv. crist. Müll. var. sibirica Midd, (1851) & V. cristata 

 Midd., Gerstf. & Scbrenk. 



— var. frigida Westerl. 1873: testa transversim striata, 

 vix nitidula, obscura. 



Hah. in Sibiria prope Jenissei ad Lusino (lat. 68 ^ 35'), 

 Surgutskoj (lat. 62» 50') et Worogowa Selo (lat 60 « 

 50') saepius frequens. Var. ad Worogowa Selo. Testi- 

 bus clariss. Middendorff, Gerstfeldt et Schrenk haec 

 species ubique in Sibiria tota et ad Amur occurrit. 



