MADEIEAN GROUP. 149 



on the Canico road, and near the Lazaretto, it is sometimes 

 comparatively plentiful. 



The H. lenticula is a species of a widely acquired range ; 

 and the nature of its habitat, within the cultivated districts, is 

 at once suggestive of a variety of methods by which it may 

 have been accidentally transported from one island, or country, 

 to another. It has established itself at the Azores, and I have 

 myself obtained it in the whole seven islands of the Canarian 

 archipelago ; and it was found by Dr. H. Dohrn in Sao Nicolao 

 of the Cape Verdes. 



I am not aware that the H. lenticula has occurred hitherto, 

 at all events in the Madeiran 1 Group, in anything but a recent 

 state, — the manifest indication, too, which it possesses, of its 

 having been originally naturalized, being against the hypothesis 

 that it was ever an associate of the various species of the sub- 

 fossil period ; and yet the Baron Paiva records it in a subfossil 

 condition from Porto Santo. I believe however it would be 

 found, on enquiry, that his specimens were merely bleached and 

 decorticated ones (such as I have often met with),— tilled up 

 with hardened sand, and drifted by the wind on to the calca- 

 reous beds in which the ordinary subfossil forms lie loose and 

 scattered over the surface, and not unfrequently intermingled 

 with others in a living state. And this is all the more probable, 

 through the Baron having likewise cited as subfossil, both from 

 the same island and Madeira, the H. jpisana, Mull., — which I 

 have every reason to believe does not exist truly semifossilized. 2 



(§ Cheilotrema, Leach.) 



Helix lapicida. 



Helix lapicida, Linn., It. Del. et Gotthl. 8 (1764) 



„ Drap., Hist. Nat. 111. t. 7. f. 35-37 (1805) 



„ „ Pfeiff., Mon. Eel. i. 370 (1 848) 



„ „ Lowe, Proc. Zool. Soc. Lond. 197 (1854) 



Paiva, Mon. Moll. Mad. 97 (1872) 



1 At the Canaries it is a little more questionable, — I myself having met 

 with it, as it seems to me truly sufossilized, in the sandy and well-nigh unin- 

 habited district of El Charco (beyond Maspalomas) in the extreme south of 

 Grand Canary. And Mousson cites a ' var. virilis, 1 from Fuerteventura, con- 

 cerning which he seems somewhat doubtful as to whether it belongs to the 

 present fauna or to one which has passed away ; though as he does not enter 

 it into his ultimate catalogue as subfossil, it would appear as if he had come 

 to the conclusion that the specimens (which were obtained by Fritsch) were 

 merely bleached and decorticated ones. 



2 The Baron has, in point of fact, however unwittingly, settled this ques- 

 tion about the H. piscina, to at all events a certain extent, even himself ; for 

 after defining his so-called ' subf ossilized ' Portosantan phasis of the shell as 

 the 'a. altispira, semifossilis ' (thus implying it to be an exclusively subfossil 

 form), in the very next sentence he proceeds to describe the 'Animal ' ! 



