PLAKORBIS. 



not influencing the aperture, which is ovato-lunate ; umbilicus 

 wide, discovering all the previous volutions ; the whorls rising 

 gradually and spirally from the horizontal, and rounded below. 



Animal black or dusky. 



Hab. Kandahar, plentiful in tanks ; Quettah and the Kojuck 

 Pass, in marshes, and along the marshlands of the Eiver Helmund 

 at G-irishk (Hutton)-, Grangetic Provinces (Tope Cliancey}\ Pinjore, 

 below Simla (Jfutton). 



It differs from Planorbis compressus in wanting the delicate 

 carina at the periphery and in having a lunate aperture without 

 the angle on the middle of the outer lip ; in being more convex, 

 with rounder whorls ; and in having its volutions wound round 

 on a more open and less horizontal twist. 



235. Planorbis (Gyraulus) labiatus (Benson}. 



Planorbis (Gyraulus) labiatus (Benson), A. AT. X. II. ser. 2, v y 

 1850, p. 350. 



Original description : Testa solidiuscula, plano-depressa, niticla, 

 albido-cornea, subdiaphaua, oblique arcuato-striata, striis remotius- 

 culis spiralibus decussata ; apice profunde concavo; sutura 

 profunda ; anfr. 3|, cito crescentibus, convexis, ultimo antice 

 majori, ab axe superiorum discedenti, rotundato, carina mediana 

 levissima submembranacea instructo, infra valde convexo ;. 

 umbilico subaperto profundiori, margine interiori subangulato ; 

 apertura obliqua, cordiformi, intus albo-labiata ; margine superior! 

 arcuato, inferiori rotundato. 



Alt. scarcely 2, diam. inaj. 5, diam. min. 4 mm. 



Fig. 5. Planorbis (Grt/raulus) labiatus, Bens. (Types.) 

 1, spire ; 2, base of shell. X 4. 



Hab. Moradabad (found amoog specimens of Planorbis 

 pressus, Hutton). 



' This Jittle shell is remarkable for the departure of the last 

 whorl from the axis which governs the previous volutions. This 

 is especially apparent underneath, where the earlier whorls in the 

 umbilicus proceed regularly, the last whorl becoming suddenly 

 excentric. The whitish rib within the lip is also a marked 

 character, as well as the proportion of the axis to the diameter." 



