﻿P L A N R B I S. 



Plate IV. 



Species 25. (Mns. Sowerby.) 

 Planorbis BiANauLATUS. Pla. testa altiuseuld, solidd, 

 jumoso-fiiscd, utrinqtut angulaiim late umhilicatd 

 deutrali ; anfradihus paucis, supra {iifrdquf ■■iiih- 

 carinatis, aperturd suhtrigond, declivi, iiij'ni iicu- 

 niiiiatd lahio externo intas incrassato. 

 The two-angled Planorbis. Shell rather high, solid, 

 smoky-brown, angularly broadly umbilicated 

 ou each side ; whorls few, keeled above and 

 below ; aperture subtrigonal; .sloped, acuminated 

 below ; outer lip thickened within. 



? Sowerby. 



Hah. Brazil. 



The whorls are not flattened at the top, as in T'la- 

 tKyrbU hicarinatus, but the lower funnel-shaped umbi- 

 licus is very similar. 



Species 20. (Fig. a, b, Mus. Brit.) 



Planorbis costhlatds. Pla. iestdparvd, compressitisimd, 

 oblique concentrich costidatd, cccruleo-subvindi ; 

 anfractlbus paucis, rapide erescentibiis, supcme 

 h'lite coHvexis, ultimo magno ; aperturd oblique 

 suhovatd, disco inferiori subplamdato. 



The ribbed Planokbis. Shell small, very compres.sed, 

 obliquely concentrically ribbed, greenish blue ; 

 whorls few, rapidly increased, slightly convex 

 above, last large ; aperture obliquely rather 

 oval ; lower disc a little flattened. 



Krauss. Sudafrikan. llollusken. Tab. V. f. S. 



Hob. Natal. 



Species 27. (Fig. «, b, Mus. ? Copied.) 



Planorbis Bengalensis. Fla. testa compressd, tenni, 

 pallide succined, Imvi, snperne convexd, iiifrd pla- 

 nulatd, anfractlbus tribus, apicalibus paulu de- 

 pressis ; umbilico basali parvo ; aperturd subtri- 

 iJOIld. 



The Bengai. Planorbis. Shell compressed, thin, pale 

 amber, smooth, convex above, flattened below, 

 whorls three, apical a little depressed, basal um- 

 bilicus small ; apertnre subtrigonal. 



DuNKER. Index Molluscorum. Tab. IT. f. 1-4. 



Hah. Bengal. 



This shell does not appear from Dunker's figure 

 to have the chambered character of the Segmentina 

 group, as shown in Planorbis calatkus, which it 

 somewhat resembles otherwise, although not nearly 

 so tumid. 



spir 



Species 28. (Mus. Sowerby.) 



Planorbis affinis. Pla. tesid corned, tumidd: 

 COiiraed, aiij'nhiilnis 'iniiiis ulliiisnilis, pni/n 

 ram snhaifjnl„li,,i ehvntix, hnn d.rliri/,„s, 

 rctundatis, npicli ,,hbet.> ; <iprrlurd ,„nji 

 superne depre.'<s<l. 



The related Planorbis. Shell horny, tumid : 



concave, whorls five, rather high, subangularly 

 elevated near the suture, then sloped, rounded 

 beneath, the apical one hidden ; aperture rather 

 large, depressed above. 



Adams, C. B. Conchological Contributions, p. tk 



Hab. Jamaica. 



More depressed and slight than Planorbis eurncus, 



with the whorls beneath more deeply sunk in the 



nmbilicus. 



.b.) 



ddi 



Siieeies 20. (Mus. Brit. So 

 Planorbis declivis. Pla. lestd altd, amjudlii: 



corned Vel xuhcaMaii.d, Iruiii-'.-^inii liratd : 

 phnu\hculd. a.ijractibu^ niKji.sfi^. nil,,,,,, ,„ 

 superne an,jiisti' ,/t,-i;il,i, turn ,lrclivi, infra r,,t 

 disco inferiori profuiide concavo, anfractibii 

 tundis; apiTturd magna, auriformi, infra 

 expanso, pruducto. 

 The sloped Planokbis. Shell raised, rather narrow, 

 horny, or chestnut, very finely ridged ; spire 

 rather flat, whorls narrow, last large, narrowly 

 raised above, then sloped, rounded below, lower 

 disc deeply concave, whorls rounded, aperture 

 large, ear-shaped, much expanded and produced 

 below. 

 Sowerby. 



Hab. ? 



Difliering from Planorlis corneas in the narrowness 

 and elevation of the whorls, and in the great expan- 

 sion and production of the lower part of the mouth. 



