﻿PLANORBIS.— Plate VI. 



Species 49. (Pig. a, h, Mus. Brit.) 



Planorhis tekveksanus. Pla. testa tuviidd, jnllli- 

 dissimi' coni"d, lannijatd; spird jjarvd, plaindaid, 

 anfractibus trihiis, ultimo timiido, supra sutiirain 

 rotnndii elevato ; apeiiurd ohliqud, mujusid, su- 

 jii'viir stilidiJatatd ; disco iiiferiori conairu. 



The THEEE-TUENEf) Planorbis. Shell tumid, very 

 pale horn, smooth ; spire small, flattened ; whorls 

 three, last tumid, roundly elevated above the 

 sutare ; aperture oblique, narrow, rather dilated 

 above ; lower disc concave. 



D'Orbigny. ? MS. Coll. Cum. in Brit. Mus. 



Hah. St. Thomas, West Indies. 



Species 50. (Pig. a, b, Mus. Brit.) 

 Planorbis Andecolus. Pla. testa alhd, altd, dctraU ; 

 spird subcomplatiatd, anfradihns trihus, conoexls ; 

 ultimo maxima, altissimo versus viarginem supe- 

 rinrem et paid!) svpra medium, aurjulato infra, ad 

 marginem iiikri^rem suhrariiinlo, jiu:<l ,;irinam 

 late, et profimd: ,niihii;<;,l,, ; „ju^rf<n:! imido de- 

 pressd, frigond, <nitif' prudnrtd, ,iciniii mitd, .<».- 

 jirnie lata, subdepressd. 

 The Planorbis of the Andes. Shell white, high, 

 dextral ; spire rather flattened ; whorls three, 

 convex ; last very large, very high, angular near 

 the upper margin and a little above the middle, 



slightly keeled at the lower margin, broadly and 

 deeply umbilicated behind the keel ; aperture a 

 Httle depressed, trigonal, anteriorly produced, 

 acuminated, broad, rather depressed aliove. 



D'Oriiicny. Voyage dans I'Amerique Meridionale, 

 PL XLV. 



Hah. Sdufli America. 



Species 51. (Mus. Brit, i 



Planorbis tenagophilus. Pla. testa, compressd, su/idd, 

 (jrisi'o-fitlvd ; utrinque conaavd ; apice umbilicatu ; 

 niijradihus qidnqiie, supra suturam angidatis ; 

 ultimo magno, superne deelivi, infra siibventncosd, 

 disco inferiori lata, versus marginem- complanato, 

 m.edio (haud profunde) umhilicato. 



The shallow-water Planorbis. Shell broad, com- 

 pressed, solid, fulvous-gray ; concave on each 

 side ; apex umbilicated ; whorls live, angular 

 above the suture, last large, sloped above, some- 

 what ventricose below, lower disc broad, flat- 

 tened towards the margin, umbilicated (not 

 deeply) in the middle. 



D'Orbigny. Voy. Amor. Meridionale, PI. XLV., 

 f.17-20. 



Hal. South America. 



The funnel-shaped umbilicus on the spire is 



naiTower and more decidedly angular than in Plan. 



orbis commutatus. 



