PLANORBIS. 91 



This is in all probability the Helix planorbis of the 

 1 Fauna Suecica,' which is described as "plana" and 

 " margine prominulo ; " but as the description and figure 

 given by Lister, to which Linne* there refers, apply to the 

 Helix complanata of the latter, more confusion will be 

 avoided by the adoption of Mliller's name. 



9. P. COMPLANA'TUS*, Linne". 



Helix complanata, Linn. Syst. Nat. ed. x. p. 769. P. marginatus, 

 F. & H. iv. p. 155, pi. cxxvii. f. 1-3. 



BODY of a deep violet-red, with very fine black specks, 

 especially on the edges of the foot : tentacles very long and 

 slender, bluntly pointed : foot rounded in front, convex 

 behind, and ending in an obtuse tail. 



SHELL concave above and slightly convex below, rather 

 solid and opaque, not glossy, yellowish-horncolour with some- 

 times a tinge of brown, closely but irregularly striate in the 

 line of growth and more or less distinctly striate in a spiral 

 direction : epidermis rather thick : periphery strongly keeled 

 on the under side : whorls 6, the diameter of the last being 

 about one-fourth of the whole spire, convex above and 

 slightly so beneath, sloping abruptly on the upper, and 

 gradually on the lower side to the periphery : suture mode- 

 rately deep : mouth roundish-oval, slightly angulated above 

 by the keel, the inside being sometimes strengthened by a 

 rib : outer lip a little reflected : inner lip continuous with 

 it and affixed throughout to the columella : umbilicus broad 

 id very shallow. L. 0-125. B. 0-6. 



Var. 1. rhombea. Shell smaller, more solid, rather more 

 ivex above and deeply umbilicated below ; keel blunt and 

 lost obsolete. Helix rhombea, Turton, Conch. Diet. p. 47. 



Var. 2. albida. Shell whitish or colourless. 



HABITAT : Marshes, ponds, canals, ditches and stand- 

 ing water everywhere in England, Wales, and Ireland ; 

 but I am not aware of any Scotch locality. It is one of 

 our upper tertiary fossils. The variety 1. is from Dublin 



* Flattened. 



