194 



SOUTH AFRICAN NOTES. 



By E. VV. S wanton. 



(Read before the Society, April q, 1902). 



Abundance of Helix pisana. — During a recent visit to Cape 

 Town with Professor Jonathan Hutchinson, F.R.S., I observed 

 Xerophila pisana in enormous numbers on an enclosed piece of ground 

 about fifty yards from the coast at Sea Point, a suburb of Cape Town. 

 Every blade of the scanty herbage, the under surface of every stone, 

 the iron supports to the wire fencing, and even the greater part of a 

 high stone wall which bounded the enclosure on one side were 

 covered with these snails. On many sticks and twigs they were 

 crowded like grapes in a large cluster. The weather was extremely 

 hot, and they were all quiescent. I regret that I had no opportunity 

 of seeing them in activity after a storm. Is Helix pisana an alien at 

 the Cape? This was the only spot where I observed them on the 

 mainland. Some fear was expressed by residents that they might 

 extend their range, and ultimately invade the Public Gardens. The 

 destruction caused by them when present in great numbers is very 

 considerable. On visiting Robben Island — the great leper prison in 

 Table Bay — I there found them in almost equal abundance, in fact, 

 the interior of the island simply swarmed with them. I was told that 

 their introduction dated from a few years ago, when it was premised 

 that some had gained the island on wreckage from Sea Point, seven 

 miles distant, where they were at that time frequent. The officials 

 on the island were much perplexed as to how to cope with the 

 'plague of snails' which were rapidly destroying all the herbage. 

 It was suggested that the introduction of a few ostriches— preferably 

 females and young birds, adult males being dangerous during the breed- 

 ing season, would soon bring about the desired effect, for these birds 

 are voraciously fond of small molluscs. 'I'he type and varieties lineo- 

 lata Moq. and albida Moq. occurred, the last was, perhaps, the more 

 abundantly represented. Phasis scapensis also occurs here. The 

 beach of this dreary island — the home of lepers, convicts, and lunatics 

 — is rocky, surf-bound, and strewn with much seaweed. Amongst the 

 boulders Patella conipressa, P. rustica and Oxytele merula occur in 

 some numbers, but none with the living animal. 



Durban Bay. — On the sandy shore of Durban Bay I found Bnllia 

 rhodosto7na Gray and B. natalensis Krauss. The latter was the more 

 abundant; it was very interesting to note the facility with which it 

 burrowed into the sand and hid itself from view upon being left behind 

 by a retreating wave. A species of lanthina and Spit ula peroni were 



