No. 6(l92l) COMMON MOLLUSCS OF SOUTH INDIA 



149 



white Helix {Helix [PLniispini] vittata), coloured red brown within the 

 mouth cavity, is seen everywhere in the Tinnevelly and Ramnad 

 districts on babul thorns and other dry-district bushes. They are 

 reputed to have a bitter taste and this probably accounts for their 

 immunity from attack by birds; their white shells are extremely 

 conspicuous on the dark leafless thorns in the hot weather when 

 bird food is scarce. During this period our Indian land snails lie 

 dormant, closing the aperture of the shell by mucous secretion that 

 dries hard and prevents evaporation from within. As this resting 

 stage occurs in hot countries during summer it is termed aestivation ; 

 it parallels the winter rest or hibernation of animals in temperate 

 and cold, countries. 



In Ceylon a huge snail, Achatina Jiilica, whose home is Africa, 



was introduced some years ago and 

 is now a recognized pest, causing 

 considerable loss owing to its depre- 

 dations in vegetable gardens in the 

 low-country region. It is an ovoid 

 shell with well developed conical 

 spire, and grows to a length of five 

 inches. Its eggs are bright yellow 

 and about one-tenth of an inch in 

 diameter. Hitherto it has not 

 obtained a footing in Madras and as 

 it is important to be able to recog- 

 nize it, a figure is given here (fig. 35). 

 Any occurrence in Madras should be 

 immediately reported and specimens 

 forwarded to the Agricultural 

 Department in order that its com- 

 plete destruction may be effected 

 l)efore it makes good its footing. In 

 Bengal it has been established for 

 over 60 years and is common in Calcutta gardens. 



Of very different appearance are the little EAR-SHELLS, Aiiri- 

 cuUdae; one species is very common among the roots of mangroves 

 in tidal back-waters, and others in moist spots near the sea. The 

 shells are oblong or oval with a well developed spire ; the outer 

 and inner lips are thickened and expanded ; in one common 



Fig. 35. Shell of Achatiua jiilica. 

 Natural size. (Ceylon.) X I. 



