PLANORBIS. 115 



solid, polished, shining, pale yellowish horn colour; whorls 4, 

 shouldered above, marked with rather coarse lines of growth ; 

 sutures deeply impressed ; columella descending obliquely and 

 diffused above into a thick callus which joins the upper margin 

 of the peristome ; peristome simple ; aperture ovately, inversely 

 auriform. 



Alt. 8'5, diam. maj. o-2o. 



Aperture: alt. 5, diam. 3-75 mm. 



//ab. Te-ring Gompa, 14,000 feet; Mang-tsa, 14,500 feet; 

 High Hill, Gompa, Gyautse A^alley, 14,500 and Gyantse, 13,120 

 feet, in small streams. 



" Mr. Bowell informs me that the radula bears a strong re- 

 semblance to that of L. gJalim^ Miill., but has fewer laterals, the 

 general appearance being more suggestive of the radula of a 

 Phinorhis than that of a Limnaa ; the maxilla is also very 

 remarkable, \\ith a large blunt beak arising from the centre of 

 the semicircular piece." 



Subfamily PLANORBIINiE. 



Shell sinistral, spire flattened or elevated. 

 Distrihutlon . AVorld-wide. 



Genus PLANORBIS. 



Planorbis, GeofEroy, Coq. de Paris, 1767, pp. 12, 81 ; Guettard, 



1756 (pre-Jjiimean). 

 Coretus, Adamsou, 1757. 

 Helix (pars), Linnaeus, 1758. 

 Aiif/ariits, Martens, 1773. 

 Orbis, Schriiter, 1776. 

 Nautilus, Lightfoot, 1786. 



Type of genus, P. comeus. Linn. 



Ramie. World-wide. 



Shell spiral, sometimes sinistral, spire tlepressed, whorls .*} to 7; 

 aperture semilunar, or ovate or trigonal, margin generally tiiiii. 



227. Planorbis exustus, Besli. 



Planorbis exustus, Uesh., Belaug. Voy. Ind. Orient., Zool. 18-34, 

 p. 417, pi. 1, tigs. 11-13; ed. Lam. viii, p. 392; Muller, Synupsis 

 Test. p. 34. 



Planorbis indicm, Benson, .T. A. S. B. v, 1836, p. 743 ; Martens, 

 Mai. Bliitt. xiv, p. 212 ; H. & T., C. I. pi. 39, tig. 10, .V: pi. 4(», 

 tig. 10; Sowerby, in Reeve, Couch. Icon, xx, pi. 4, fiir. 31; 

 Clessin, in Conch.-Cab. 1886, p. 43, pi. 6, ficrs. 20 22, c*c p. IKi. 

 pi. 17, tigs. 1, 2. 



Orhjinal description : — Testa orbiculata, utroque latere depressa, 

 sutus concaviuscula ; anfractibus convexis, teiiue striatic 



i2 



