172 TESTACEA ATLANTICA. 



granulated race is by no means constant, some examples being 

 much more trochiform than others ; whilst as regards colour, it 

 passes through a nearly endless number of changes, certain spe- 

 cimens being comparatively pale and unbanded, though by far the 

 greater number are very highly decorated, the fasciae being- so 

 enlarged as to cover most of the surface except a sutural line, the 

 region outside the aperture, and the central area beneath. The 

 umbilicus is tolerably large and spiral, and the keel is rather 

 sharply expressed. 



This normal phasis (as we can scarcely help regarding it) of 

 the H. polymorpha occurs only in Madeira proper, and is emi- 

 nently characteristic of the eastern half of the Sao Lourenyo pro- 

 montory (itself in the extreme east of that island), attaining its 

 maximum on the detached insular termination of it known as the 

 Ilheo de Fora (where it has been taken in profusion by Mr, Lowe, 

 Mr. Watson, Dr. Grrabham, myself, and others). 1 The examples 

 from the actual Ponta de Sao Lourenpo have all their characters 

 rather less exaggerated than in those from the Ilheo de Fora, 

 thus showing a manifest tendency to merge into the other 

 coarsely granulated but less conical form (the ' /3. salebrosa ') 

 which occurs both to the north and south (i. e* towards Porto 

 da Cruz, and towards Machico) of that low rocky tongue of land, 

 and which indeed crops up even so far away as the Ponta de Pargo, 

 the north-western point of Madeira. 



Common as it is towards the extremity of the Sao LourenO 

 promontory, I am not aware that this typical phasis of the H. 

 polymorpha has ever yet been observed in the subfossil deposits 

 (so near at hand) of Canipal. 



ft. salebrosa, Lowe. 



Helix polymorpha, y., Pfeiff., Mai. Blatt. 81 (1852) 



senilis, Lowe [nee Morelet, 1851], Ann. Nat. Hist. ix. 



116 (1852) 



Id., Proc. Zool. Soc. Lond. 189 (1854) 

 polymorpha, var. 7., Alb., I. c. 26. t. 5. f. 16-18 



(1854) 



salebrosa, Lowe, Ann. Nat. Hist. x. 95 [note] (1862) 

 polymorpha, var. /Q., Paiva, I. c. 84 (1867) 

 Habitat Maderam, et tres Desertas ; in aridis apricis mariti- 



1 I may add that this shell has never been observed by at any rate either 

 Mr. Lowe or myself in the neighbourhood of the fossil-bed and the Piedade, 

 but always on the red Tufa soil nearer to the actual Point, where, during 

 the winter months, it may be found attached to the stems of plants and low 

 bushes (particularly of Sahola fruticosa), beyond (i.e. to the eastward) of the 

 arch-rock in Labra. 



