455 



dufky, or greenifh epidermis when alive : dead {hells 

 become white. 



Animal dufky, with two long, flender, filiform, ten- 

 taenia; and two black eyes placed at their bafe. 



63. 

 Helix Spirorbis. Gmel. Syfl. p. 3624. 36. Spirorbis. 



PlanorbisSpirorbis. Midler Venn. ii. p. 161. No. 347. 



Schroeter FhJfcoJick. p. 236. No. 47. 



Id. p. 229. t. 5. f. 1.8. 



H. with a depreflfed, fub-pellucid, horn-coloured 

 (hell, with fix volutions, placed exaftly lateral upon 

 each other, fo that both the upper and under fides are 

 equally flat; the volutions, however, are as much convex 

 beneath as they are above, and the exterior whirl is nearly 

 round, and deftitute of any carina : aperture oval, in 

 fome nearly orbicular. Diameter of the largefl three- 

 tenths of an inch. 



• This fpecies is not uncommon in the fame place as the 

 H. Vortex, with which it has generally been confounded 

 in EngliJJi cabinets. 



MuLLER has very well defined the diftinftion by fay- 

 ing, " Planorbis tefia flavefcente, utrinque concava, aiqua- 

 li ; anfraElibus teretibus." This, when compared with 

 his leading charafters of the Vortex, will be found to be 



ftrong 



