44 THE ZOOLOGIST. 



I was in Calcutta in 1876-77 an African species of Achatina 

 spread all over the gardens of Chowringhi and the suburbs, to 

 Howrah on the other side of the River Hooghly, and to Barrack- 

 pore, about fifteen miles north. It had been introduced origi- 

 nally into Calcutta by Mr. Benson some twenty years before, 

 after his arrival from the Cape and the Mauritius." This 

 account places the date of introduction at something over fifty 

 years ago. 



The origin of the present outbreak in Ceylon has been traced 

 to the fact that the late Mr. Oliver Collett (an enthusiastic 

 collector of land Mollusca) received some living examples of the 

 species (either from India or Mauritius) some ten years ago. He 

 liberated them in his garden, where they soon showed signs of 

 becoming naturalized. Acting upon advice, he collected and 

 destroyed them, and it was thought that he had been successful 

 in exterminating the whole brood. But it has now been ascer- 

 tained that the snails are still to be found in the locality of their 

 original introduction. This is situated in the Central Province 

 of Ceylon, at an altitude of between four thousand and five 

 thousand feet, where the climatic conditions appear to be un- 

 favourable to their excessive increase. The outbreak that has 

 now attracted attention is at sea-level, on the south-western 

 coast of the island, the two localities being distant over fifty 

 miles in a direct line, and having no natural communication by 

 water. But the existence of a family of natives having connec- 

 tions in the two places affords an explanation that will meet all 

 the circumstances of the case. It is, in fact, known that one of 

 these natives, on his return from a visit to his friends up-country, 

 brought down a parcel of vegetables amongst which two of these 

 snails were discovered. 



It is to be remarked that neither in Mauritius nor in India, 

 where the snail has been established for over half a century, is 

 it considered to be a pest of economic importance. In the 

 former country its value as a scavenger is recognized. The 

 smaller individuals are occasionally troublesome in the vege- 

 table and flower garden, but not more so than the garden snail 

 of Europe, and it has not been recorded as destructive to any 

 field crops. The full-grown snail appears to devote itself more 

 exclusively to the removal of decaying and offensive matter. 



