30 TEST ACE A ATLANTIC A, 



Helix Drouetiana. 



Helix Drouetiana, Morel., Hist. Nat. des Agor. 160. t. 2. 

 f. 5 (1860) 

 „ „ Drouet, Faun. Agor. 15S (186\) 



Habitat Fayal ; ad orientem montium versus Caldeira ascen- 

 dentium, sub lapidibus rarissima. 



This species appears to be a trifle larger than the three 

 preceding ones, having about the same expanse (13 millimetres) 

 across its broadest part as the H. azorica — with which also it 

 agrees somewhat in its general type of colouring, in the fine- 

 ness of its striation, and in its ultimate whorl being a little 

 widened. It is however more solid and less transparent than 

 the azorica and caldeirariimi ; its spire is appreciably more 

 acute and prominent ; and its peristome is more decidedly 

 thickened within, and has the columellary margin more flattened 

 or expanded. From the H. azorica it further differs in its 

 aperture being less rounded, and in its axis being shorter (or 

 less vertically visible) at its point of junction with the lower 

 lip. In ornamentation the H. Drouetiana is of a pale yellowish 

 brown, but variegated with more or less evident and irregular 

 transverse radiating lines of a more corneous hue ; and there is 

 usually a darker, interrupted, or broken-up zone at the circum- 

 ference of the basal volution, and which runs alongside the 

 suture of the penultimate one. 



The H. Drouetiana was met with by M. Drouet in Fayal, — 

 towards the east of the mountains which rise so as to form the 

 Caldeira ; where, moreover, it would appear to be scarce. 



(§ Pomatia, Beck.) 



Helix aspersa. 



Helix aspersa, MillL, Verm. Hist. ii. 59 (1774) 



„ „ Pfeif., Mon. Hel. i. 24:1 {184:8) 



„ „ Morel, Hist. Nat. des Agor. 152 {I860) 



„ „ Drouet, Faun. Agor. 151 (1861) 



„ „ Mouss., Faun. Mai. des Can. 69 (1872) 



Habitat ins. omnes (sec. Morelet et Drouet) ; in cultis late 

 sed vix copiose diffusa. 



According to Morelet and Drouet, the common H. aspersa, 

 Miill., occurs on every island of the Azorean archipelago, where 

 doubtless it must have been introduced from the European conti- 

 nent. It is a species which is extremely liable to accidental trans- 

 mission, along with consignments of trees and plants ; and it was 

 in all probability in that manner that it has become thoroughly 

 naturalized at St. Helena. Into Madeira it was imported a 



