PLATE XCIX. 



HELIX CONTORTA. 



THICK RIVER CHEESE SHELL. 

 GENERIC CHARACTER. 



Aperture of the mouth contracted and lunulated, 



SPECIFIC CHARACTER 



AND 



SYNONYMS. 



Shell thick, umbilicated, flattish. Aperture narrow and crescent- 

 shaped. 

 Helix Contorta : testa subuitibllicata plana utrlnque cequali : 



apertura lineari arcuata. Gruel. Linn. Sj/sL Nat. 



p. S624. 

 Planorbls minima crassa TIney many-clrcled, thick, river cheese 



shell. Petiv. Gaz. tab. 92. fig. 8. 

 Planorbls minima crassa, utrlnque umblllcata, anfractlbus subde- 



pressls. Crassa. Da Costa Br. Conch, p. &Q. 



sp. 37. Tab. \.fig. 11. 



G 2 



