MADEIRAN GROUP. 173 



mis hinc inde viilgatissima. Semifossilis ad Canijal Madera^ 

 parcissime sed in summo Desertoe Australis copiosius inveiiitur. 



While the last (or normal) state of the H. 'polymorpha is 

 characteristic of a limited district in the extreme east of Madeira 

 proper, the present one makes its appearance in many parts of 

 the eastern and northern coast of the same island, extending like- 

 wise to the Desertas, — on the whole three of which it occurs, 

 though more particularly on the central or larger one. The Ma- 

 deiran examples however are not usually quite similar to those 

 of the Desertas, — being, on the average, a little more sharply 

 keeled and more coarsely granulated ; and they are generally too 

 a trifle thinner (or less solid), and not so highly coloured : indeed 

 I possess a series of them from the Ponta cle Pargo (perhaps 

 somewhat exceptional) which are nearly devoid of markings. 



Although extremely variable in the elevation of its spire, the 

 ' /3. salebrosa ' is considerably less conical than the (so-called) 

 type, it being altogether flatter and more lenticular ; but the 

 Madelran phasis of it is, I think, quite as strongly asperated as 

 the latter with powerful granules. The Desertan specimens are 

 usually less coarsely granulated, particularly above, and their 

 keel is a little more obtuse ; but both of these features are svibject 

 to considerable variation. As for the mere development of the 

 bands (which are for the most part more conspicuous in the De- 

 sertan race than in that from jMadeira), hardly two examples have 

 them precisely alike. 



The ' /S. salebrosa ' (wliich is so common on the Desertas, par- 

 ticularly on the central island) was found by Mr. Lowe in Madeira 

 proper, — namely on the Larana promontory below Porto da Cruz, 

 and at the Ponta de Pargo ; and it occurs likewise between Ma- 

 chico and Sta. Cruz. In a subfossil condition it is not uncommon 

 on the summit of the Southern Deserta, but extremely rare in the 

 calcareous deposits near Cani^al.' 



y.poromphala, Lowe. 



Helix polymorpha, 8., Pfeif., Mai. Bldtt. 81 (1852) 



„ poromphala, Loive, Ann. Nat. Hist. ix. 116 (1852) 

 „ senilis (pars). Id., Proc. Zool. Soc. Lond. 189 (1854) 

 „ polymorpha, var. S., Alb., I. c. 26. t. 5. f. 19, 20 (1854) 

 „ „ var. /S. (subv. 1), Paiva, I. c. 84 (1867) 



Habitat tres Desertas ; prsecipue in insulis Boreali et Australi 

 congregans. In Deserta Australi semifossilis quoque reperitur. 



' As reg-arcls the synonymy of -this shell, I may acid that the name ^senilis'' 

 having been preoccupied by Morelet during the preceding year to that in 

 which it was employed by Mr. Lowe, it became necessary for the latter to 

 propose a fresh one, — which he consequently did in 18G2. 



