372 JOURNAL OF 1 CONCHOLOGY, VOL. 9, NO. 12, OCTOBER, 190O. 



almost membraneous and could with ease be indented by the finger 

 nail, whilst to let one fall when wet was instant destruction to the 

 specimen. The specimens obtained at Aranci Bay in Sardinia were 

 also frail, but not in so marked a degree. 



The following well-known varieties were observed: — 



V^r. marmorata. — This variety I only found at Gibraltar and 

 there confined to a comparatively small area near the Windmill Flats, 

 though an occasional sporadic specimen was rarely met with in other 

 parts of the Rock. 



Var. minor. — Curiously enough this variety is also only to be 

 found at Gibraltar, where it is sparingly to be met with in the higher 

 parts of the Rock. 



Var. unicolor. — I am of opinion from my own small observations 

 that this variety, so rare in Great Britain, is one of the commonest on 

 the Continent. At Arosa Bay about sixty per cent, of all specimens 

 were of this variety, and at Aranci Bay about fifty per cent. At 

 Gibraltar I have taken this variety once only. It was possible at 

 Arosa Aay to get together a large series of shells of H. aspersa showing 

 a complete transition from the typical form to this variety, so that I 

 think one may safely regard all feebly marked specimens as steps on 

 the way towards the suppression of markings altogether. 



Var. zonata. — The bulk of the specimens taken at Algerciras 

 were of this variety. It occurred also somewhat sparingly at Gibraltar 

 and was decidedly rare at Arosa Bay. 



H. conspurcata (Draparnaud). — Dr. Kobelt says of this species 

 that it occurs here and there and not too commonly at Gibraltar. As 

 a matter of fact I found it now very local, but also plentiful after rain, 

 in the Alameda Gardens and the road just above them and during 

 the autumn months. In March, April and May I have quite failed to 

 discover a single specimen. 



H. apicina (Lam.). — When Mr. Ponsonby first found this species 

 at Gibraltar in 1883 it was confined to the North Front, but now it 

 has spread considerably, and is found all over the lower parts of the 

 Alameda Gardens and as far as Rosio Bay to the south. I saw one 

 specimen of the species at Cagliari in Sardinia. 



H. acuta (Miiller). — This species occurs in countless thousands 

 on the North Front at Gibraltar, though it is also met with high up 

 the Rock, in the Alameda Gardens, and, in fact, all over the fortress 

 besides. Some of the specimens are of great size, but such are rare. 

 I also took this species in some quantity at Aranci Bay and Cagliari 

 in Sardinia, but on the Spanish mainland adjoining Gibraltar I could 

 not find it. 



