336 THE APPLE-SNAIL. 



it escapes observation, and does much damage without being discovered. Those who desire to 

 rid their gardens of these pests will find that a very effectual plan is to search the grounds 

 after dark, by the aid of a " bull's-eye" lantern. 



THE semi-spiral shell, called TESTACELLA, is one of the very few carnivorous land 

 mollusks. 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; the English species is 

 supposed to have been introduced from Southern Europe. 



WE will now pay attention to the Water ^snails, several of which can be found in every 

 large pond or stream, and at first we may regard two species of APPLE-SNAILS, belonging to a 

 genus remarkable for several peculiarities of formation. Although the Apple-snails belong 

 more properly to the gill-bearing mollusks, and follow in the systematic arrangement the 

 phorus, described on page 328, we placed them with the pond-snail and planorbis, for the 

 reader's convenience of having combined on a few pages the various water-snails. 



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 remaining 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 muddj 

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

 preserved when the tanks evaporate, to reappear in full growth and vigor immediately 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. 



"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 water- 

 course 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. 



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 and stout footstalks, and the enormously long tentacles 

 are placed just in front of the eyes. At the first glance the creature appears to have four 

 tentacles, but on a closer examination, the front pair are seen to be merely developments of 



