408 THE APPLE-SNAIL. 



Another useful plan is to make an attractive shelter from boards or tiles, and place 

 cabbage-leaves within. The Slugs will crowd to the bait during the night, and, finding 

 themselves sheltered, will remain there during the daytime, when they maybe captured 

 and destroyed. 



ON the left of the illustration on page 405 may be seen a little Slug with a semi-spiral 

 shell, represented as crawling up a short stump. 



This is the TESTACELLA, one of the very few carnivorous land molluscs. The 

 Testacella, although plentiful, is seldom seen, on account of its peculiar habits. It feeds 

 almost wholly on earth-worms, which it pursues through all the windings of their 

 retreats, its long lithesome body enabling it to insinuate itself wherever the worm can 

 burrow, and its hard little shell securing it from danger by stopping up the tunnel 

 behind its progress. This curious slug can be obtained in gardens by digging up the 

 loose soil, but, on account of its services to the gardener, should be released, and 

 permitted to resume its destructive avocations. 



The tooth-ribbon of this creature is most formidably armed, having about two 

 thousand teeth arranged in fifty rows. The teeth are needle-shaped, barbed, sharply 

 pointed, slightly curved, and converge towards the centre of the ribbon, thus forming 

 a weapon which no worm is capable of resisting. Only three species of Testacella are 

 known ; our British species is supposed to have been introduced from Southern Europe. 



IN the following illustration is shown a group of Water-snails, several of which can 

 be found in every large pond or stream. 



The two central figures represent two species of APPLE-SNAILS, belonging to a genus 

 remarkable for several peculiarities of formation. Although placed with the pond- 

 snail and planorbis for the convenience of bringing the various water-snails into a single 

 illustration, the Apple-snails belong more properly to the gill-bearing molluscs, and in 

 the systematic arrangement follow the phorus, described on page 394. 



The Apple-snails are found throughout the warmer parts of the world, inhabiting the 

 lakes and rivers, and, in case of drought, burrowing deeply into the mud and remain- 

 ing buried for a lengthened period, sometimes for a term of years, until a fresh supply 

 of water arouses them from their strange torpor, and urges them again to seek the upper 

 regions. 



In his " Natural History of Ceylon," Sir J. Emerson Tennent mentions this curious 

 habit. "The Ampullaria glauca is found in still water in all parts of the island, not 

 alone in tanks, but in rice-fields and the water-courses by which they are irrigated. 

 When, during the dry season, the water is about to evaporate, it burrows and conceals 

 itself till the returning rains restore it to activity and reproduce its accustomed food. 

 There, at a considerable depth in the soft mud, it deposits a bundle of eggs with a 

 white calcareous shell, to the number of one hundred or more in each group. 



The Melania paludina, in the same way, retires during the droughts into the muddy 

 soil of the rice-lands, and it can only be by such an instinct that this and other molluscs 

 are preserved when the tanks evaporate, to reappear in full growth and vigor imme- 

 diately on the return of the rains. 



A knowledge of this fact was turned to prompt account by Mr. Edgar S. Layard, 

 when holding a judicial office at Point Pedro in 1849. 



A native who had been defrauded of his land complained before him of his neighbor, 

 who, during his absence, had removed their common landmark, diverting the original 

 watercourse and obliterating its traces by filling it up to a level with the rest of the field. 

 Mr. Layard directed a trench to be sunk at the contested spot, and discovering numbers 

 of the Ampullaria, the remains of the eggs, and the living animal which had been buried 

 for months, the evidence was so resistless as to confound the wrong-doer and terminate 

 the suit." After a few hours of rain, the Apple-snails may be observed emerging from 

 their muddy retreat as if to welcome the newly found moisture. 



As may be seen from the illustration, the animal of the Apple-snail is very curiously 

 formed. The long siphon, formed by a development of the neck-lappet, is seen on the 

 left. Projecting just without the shell are seen the eyes, set at the extremities of short 



