﻿PLANOEBIS.— Plate I. 



Species 4. (And Pig. h, PI. X., Mus. Sowerby.) 

 Planorbis corpulentus. Pla. testa tenui, inflatd, 

 suhglobosd, snhviride cornea, concentrice oblique ru- 

 gatd, altd, superne angulatd, infra suhangulatd, 

 sinistrali; spird infundibulaid, anfractiius supra 

 suturam elevaiis, angulatis, lateraliter planulatis ; 

 medio altis, convexis ; ultitno versus aperturam ex- 

 pansis ; aperturd maximd, supra infraque ulti- 

 mum anfractum produciis, superne subangustatd, 

 infer ne lata, margine expanso, intiis casianeo ; 

 disco superiori profunde uinbilicato. 



The corpulent Planorbis. Shell thin, inflated, sub- 

 globose, greenish horny, concentrically obliquely 

 -wrinkled, high, angular above, a little angular 

 below, sinistral ; spire funnelled, whorls raised 

 above the suture, angular, laterally flattened, 

 high, convex in the middle ; last expanded to- 

 wards the aperture ; aperture very large, pro- 

 duced above and below the last whorl, rather 

 narrow above, broad below, margin expanded, 

 chestnut within ; upper disc deeply umbili- 

 cated. 



Say. Albers. Mon. PI. III. f. 79. 



Hab. Winnipeck River. 



It is difficult to distinguish the less developed 

 forms of this .species from the more elevated forms 

 of Planorbis lentus. The latter is a stouter shell, with 

 the wrinkles more defined, and it is never quite so 

 high. Planorbis frivolvis is considerably more de- 

 pressed than either. 



Species 5. (Mus. Sowerby, &c.) 

 Planorbis complanatds. Pla. testa dextrali cornea- 

 fulvd, Imvigaid, compressd, superne convexiusculd, 

 inferne planulatd; spird medio subexcavatd ; an- 

 fractibus quinis, moderate crescentibus, ultimo in- 

 frd carinatis; aperturd oblique subovatd, supra 

 anfractum ulUiimm elevatd et productd. 

 The flattened Planorbis. Shell horny fulvous, 

 smooth, compressed, rather convex above, flat- 

 tened below; spire a little hollowed in the 

 middle ; whorls five, increasing moderately, last 



keeled below ; aperture obliqnely snbovate, 

 raised and produced above the last whorl. 



LiNN^us. Systema Naturte. 



Planorbis marginatus. Draparnaud. 



Planorbis umbilicatus. Miiller. 



Hab. France, England, Sicily. 



Species G. (Fig. a, b, Mus. Brit.) 



Planorbis olivaceus. Pla. testd sinistrd, depressd, 

 olioaceo-fuscd, nitenti, laid, superne declivi, infrd 

 latissimd, spird coneavd, angustatd, anfraetibus 

 senis, compressis, supra suturam patili) elevatis, 

 turn lente deelivibus ; aperturd subtrigond, mar- 

 gine inferiori oblique productd; disco inferiori 

 cmicavo. 



The olive Planorbis. Shell sinistral, depressed, 

 olive-brown, shining, broad, sloped above, very 

 broad beneath ; spire concave, narrow ; whorls 

 six, compressed, a little raised above the suture, 

 then gently sloped ; aperture subtrigonal, lower 

 margin obliquely produced ; lower disc concave. 



Spix. Testacea Braziliana, p. 26, PL XVIII. f. 1, 2. 



Plannrhis Cumivgiuiius. Dunker. Proc. Zool. 1848. 



ITab. Brazil. 



Species 7. (Mns. Brit.) 



Planorbis bicarinatus. Pla. testd siidstrali, tenui, 

 hevigatd, altissimd, pallide stramined ; spird an- 

 gustd, propemode infundibulaid, anfraetibus tribus, 

 stipenii; inferneque carinatis; ultimo anfractu 

 iiiaj'iino, ad aperturam altissimo, superne acumi- 

 tiato. infra laliiisculo ; disco inferiori profundi, 

 umhilicato, anfractu apicali ohtecto. 



The two-keeled Planorbis. Shell sinistral, thin, 

 smooth, very high, pale straw ; spire narrow, 

 deeplj- fannelled, whorls three, keeled above and 

 below ; last whorl very large, very high at the 

 aperture, acuminated above, rather wide below ; 

 lower disc deeply umbilicated, apical whorl 

 hidden. 



Sat. Jonrn. Nat. Sci. Phil. 



Hab. River Ohio. 



