t^^l

124 lIMNvEIDiE.
250. Planorbis (Gyraulus) issykulensis, Glessin.
Planoi-bis (Gyraulus) iasykulensis, Glessin, 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, compressedly ovate.
Alt. 1-2, diam. 4*5 mm.
Hah. Pamirs, from only one locality, but very plentiful.
Section HIPPEUTES.
Ilippeutes, Agassiz, Nouv, Mem. Soc, Ilelv. i, 1837.
Tl'PE, Planorbis fontanus, Lightfoot; Europe.
Jiangc. Europe; Asia.
Siieh small, lenticular, much depressed, paucispiral; whorls very
rapidly increasing, carinate ; aperture obliquely heart-shaped.
251. Planorbis (Hippeutes) versicolor, Westerlund.
Planorbis {Hippeutes) versicolor, Westerlund, in Vep^a Exped.
Vetenskapliga Jakttagelser, iv, p. 206, pi. 4, lig. 19.
Original description:—-Testa juvenis rufo-castanea, nitidissima,
adulta rufescenti-cornea, nitidula, subtilissime oblique striatula,
supra convexa, centre sat profunde immersa, subtus planiuscula,
umbilicata (umbihco centro augustissimo, aperturam versus
dilatato) striatula; anfr. 4, primi angusti, spiram minimam formantes,
ultimus maximus, extus declivis, subtus convexiusculus,
peripheria acute angulatus ; apert. perobliqua, cordiformis,
margine columellari subrecto, exteriore antrorsum valde convexo.
Alt. 1.-5, diam. 5 mm.
Mab. Point de Galle, Cejdon.
Subgenus SEGMENTINA.
Segmentinn, Fleming-, Hist. Brit. Anim. 1828, p. 279.
TypB, Planorbis nitidus, Miiller; Europe.
Mange. Europe ; A sia ; Africa ; Australia.
Shell orbicular, depressed, furnished internally with transverse,
testaceous partitions or teeth; apertflre transversely oval, or
circular.
See also description of Planorbis, p. 115.