w 



MOLLUSCA INJURIOUS TO FARMERS AND GARDENERS. 203 



the whole of England and France, and in nearly all European 

 countries. It is also met with in Siberia, Afghanistan, Thibet, 

 Amoor, Morocco, Algeria, Abyssinia, Tunisia, Canary Islands, 

 and Fseroe Islands. I do not know of its record in the Shetland 

 Islands ; the fluke, however, I think exists there. It has also 

 been found in a semi-fossil state in various recent formations, 

 and in the Upper Tertiary beds. It deposits its eggs or spawn 

 upon the mud around ponds, ditches, and streams, where 

 it lives. The eggs are laid in batches of 30 to 100, each 

 snail laying as many as 1500 eggs during its life. The 

 eggs are united in strips of a gelatinous consistency. In 

 about two weeks these give rise to the young shells. 

 Occasionally embryo flukes have been found in L. peregra of 

 Miiller, but they have always been in the young stage ; I believe, 

 however, that they use this species as a host in the same way that 

 they do truncatida. 



L. peregra. — Length about 075, breadth 0*425. Shell 

 obliquely ovate, thin, and moderately glossy, almost transparent 

 pale yellowish brown, spirally striate ; striae minute ; also a few 

 indistinct spiral ridges and marks ; whorls five, last occupying 

 three-fourths of shell ; spire of shell pointed. Body pale yellowish 

 grey, with an olive-green tinge mottled with black and covered 

 with small yellow and white specks. Extremely abundant and 

 variable. Found in lakes, ponds, canals, &c, wherever there is 

 water. Like truncatula it may be found in Afghanistan, and 

 abundantly in all Europe. It is a slow-moving creature, but often 

 wanders far from any water into damp meadows, and is sometimes 

 found crawling up willow trees. It is extremely prolific, the eggs 

 being laid in strings of 12 to 180, and as many as 1300 in one 

 season, according to Jeffreys. They are often carnivorous, living 

 one upon another if kept in an aquarium. In North America 

 L. humilis (Say) plays the part of intermediate host of this 

 Trematode worm, and in Argentina L. viator, Orb., takes the 

 place of our two species. 



Destruction of Water-Snails. — It is of course extremely 

 difficult to see how we can get rid of these water-snails; there is 

 no doubt, however, that the suggestion made by Miss Ormerod, 

 of " clearing the shallow pools of weeds and removing the broad 

 band of weed-growth or stagnant mud from the entrance end of 

 the pool," would greatly lessen the quantity of water-snails. The 



r 2 



