354 TEST ACE A ATLANTIC A. 



Helix quadricincta. 



Helix qnadricincta, Morelet, Journ. de Conch, xii. 156 



(1864) 



Pfeiff., Mon. Hel v. 371 (1868) 



Id., Novit. Conch, ii. t. 72. f. 13-16 



Mouss., Faun. Mai. des Can. 78 



(1872) 



Habitat Gromeram ; in collibus aridis apricis juxta San Se- 

 bastian vulgaris. ' Var. a. subaucta ' in locis magis elevatis 

 degit. 



Morelet's H. quadricincta seems to be peculiar to Gromera, 

 where it was taken abundantly by Mr. Lowe and myself on 

 the dry rocky slopes immediately above San Sebastian, on the 

 northern side of the ravine ; and it would appear to have been 

 met with previously by Fritsch. It is stated by Pfeiffer, on 

 the authority of the Baron Paiva, to occur also in Teneriffe ; 

 but this, I think, requires corroboration. 



The H. quadricincta, which measures about 8 lines across 

 it broadest part, is a depressed and lenticular shell, acutely 

 keeled, with about half of its umbilicus exposed (or uncovered), 

 and beset all over with simple and very regular oblique trans- 

 verse costate lines. It is rather tumid on the underside, but its 

 volutions above are flattened ; and its surface is of a pale yel- 

 lowish-corneous hue (whiter and paler beneath), but ornamented 

 with four narrow darker bands, of which one is immediately 

 above (and adjoining) the keel, another at a short distance be- 

 low it, and the remaining two on the anterior half of the whorls. 

 Its peristome (which is white and polished) is a good deal 

 expanded and recurved, the basal portion being broadly incras- 

 sated. 



There is a slightly larger phasis of this species, which is 

 found at a higher elevation, and which was taken by Mr. Lowe, 

 on April 21, 1861, immediately below the Cumbre (on the south- 

 eastern side) at the head of the San Sebastian ravine, and which 

 I should have been inclined to regard as the H. Villiersii of 

 d'Orbigny was not its keel quite as strongly expressed as in the 

 typical H. quadricincta. In addition to its being somewhat 

 larger than the latter, its costae are not quite so regular, its 

 aperture is relatively a little more developed and outwardly- 

 extended, the basal margin of its peristome is a trifle less 

 thickened and less curved, and its fasciae are just appreciably 

 less continuous, or more interrupted, giving a slightly more 

 freckled appearance to the upper portion of the shell than is the 

 case in the H. quadricincta proper, though very much less so 



