124 



250. Planorbis (Gyraulus) issykulensis, Ckssin. 



Planorbis (Gyraulus) issyktdensis, Clessin, Nachr. Bl. Malak. Ges. 

 xxxix, 1907, p. 7. 



Shell small, slightly compressed, whorls 4, rapidly increasing 

 (the last scarcely one-third of the total diameter of the shell) ; 

 suture moderately deep ; umbilicus rather wide ; sculpture fine, 

 irregular ; aperture oblique, compresseclly ovate. 



Alt. 1-2, diam. 4*5 mm. 



Hab. Pamirs, from only one locality, but very plentiful. 



Section HIPPEUTES. 



Hippeutes, Agassiz, Nouv. Mem. Soc. Helv. i, 1837. 

 TYPE, Planorbis fontanus, Lightfoot ; Europe. 



Mange. Europe; Asia. 



Shell small, lenticular, much depressed, paucispiral ; whorls very 

 rapidly increasing, carinate ; aperture obliquely heart-shaped. 



251. Planorbis (Hippeutes) versicolor, Westerlund. 



Planorbis (Hippeutes) versicolor, Westerlund, in Vega Exped. 

 Vetenskapliga Jakttagelser, iv, p. 206, pi. 4, tig. 19. 



Original description: Testa juvenis rufo-castanea, nitidissima, 

 adulta rufescenti-coruea, nitidula, subtilissinie oblique striatula, 

 supra convexa, centro sat profunde immersa, subtus planiuscula, 

 umbilicata (umbilico centro augustissimo, aperturam versus 

 dilatato) striatula ; anfr. 4, primi angusti, spiram minimam for- 

 mantes, ultimus maximus, extus declivis, subtus convexiusculus, 

 peripheria acute angulatus ; apert. perobliqua, cordiformis, 

 margine columellari subrecto, exteriore antrorsum valde convexo. 



Alt. 1-5, diam. o mm. 



Hab. Point de Galle, Ceylon. 



Subgenus SEGMENTING 



Segmentina, Fleming, Hist. Brit. Anim. 1828, p. 279. 

 TYPE. Planorbis nitidus, Miiller ; Europe. 

 Range. Europe ; A sia ; Africa ; Australia. 

 Shell orbicular, depressed, furnished internally with transverse, 

 testaceous partitions or teeth ; aperture transversely oval, or 

 circular. 



See also description of Planorbis, p. 115. 



