350 Mr. W. H. Benson on new species of Planorbis 



which I compared it, and the slope of the last whorl, underneath, 

 towards the penultimate whorl, independently of other characters 

 noted, ought to have indicated that the description was quite in- 

 applicable to PL convexiusculus, which is wound on a regularly 

 increasing open spiral, instead of rapidly increasing in the 

 breadth of the last whorl. This rapidity of increase, but in a 

 less degree, is observable in PL Cantori. PL umbilicalis, moreover, 

 could never, by possibility, have been overlooked among examples 

 of PL compressus, as Capt. Hutton states to have been the case 

 with his Pinjore specimens of PL convexiusculus. 



5. Planorbis labiatus, nobis, n. s. 



Testa solidiuscula, plano-depressa, nitida, albido-cornea, subdiaphana, 

 oblique arcuato-striata, striis remotiusculis spiralibus decussata ; 

 apice profunde concavo ; sutura profunda; anfractibus 3 J, 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 superiori arcuato, inferiori rotundato. 



Diam. maj. 5, minor 4, axis vix 2 mill. 



Hab. in stagno prope urbem Moradabad. Inter specimina PI. com- 

 pressi (Hutton) detexi. 



This little 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 cha- 

 racter, as well as the proportion of the axis to the diameter. 



6. Planorbis Sindicus, nobis, n. s. 



Testa minuta, perforata, sublenticulari, albida, lsevi, subdiaphana, 

 supra convexa ; spira planulata, apice depresso ; anfractibus 2\, 

 ultimo medio obtuse angulato, subtus convexo ; apertura cordata, 

 obliqua, margine superiori arcuato, prominente, inferiori recedente. 



Diam. 2^ mill., axis f mill. 



Hab. in fluvio Indo, regione Sindica superiori. 



This very distinct and minute species, remarkable, after PL 

 trochoides, nobis, for its small umbilicus, but of a less trochoid, 

 and more lenticular form, I found adhering to the inside of a 

 specimen of Paludina Bengalensis sent to me, with other shells 

 common to the Gangetic Provinces, from the banks of the Indus 

 above Sukkur, by my friend Major FitzGerald, Bengal Cavalry, 

 from the expedition which accompanied Shah Shujah under Lord 

 Keane to Cabul. No other specimen appears to have been met 

 with. 



