226 THE DISPERSAL OF SHELLS. 



occurred, in houses, in a tank containing seedlings of 

 Victoria regia, and in glass vessels and tanks in which 

 Vallisneria spij^alis and other aquatic plants were 

 growing. Very possibly they were introduced from 

 Kew, for Mr. W. Sowerby tells me that the Royal 

 Botanic Society is constantly exchanging plants of all 

 kinds with the Royal Gardens. The creature has 

 occurred, also, in one locality in Scotland, having been 

 collected, in 1887, from three or four ponds in the 

 grounds of the Banner Mill Company at Aberdeen. 

 These ponds, containing warm water discharged from 

 the mill, are tenanted also by gold-fish, various aquatic 

 plants, and the common wandering pond-snail {LinincBa 

 peregrd). Mr. W. D. Rae, who first collected specimens 

 in this locality, stated in 1 891 that the foreman had 

 seen the creatures in the ponds ever since he came to 

 the mill thirteen or fourteen years previously ; sixty- 

 two living specimens were collected and forwarded to 

 Mr. Rae, in London, in 1890. Presumably the animal 

 was introduced either with aquatic plants or with the 

 gold-fish.^ 



A specimen oi Lithoglyphus naticoidcs Fer., a fresh- 



* A. Choules, "Zoologist," xviii. (i860), pp. 72, 78-9; A. M. 

 Norman, "Ann. and Mag. Nat. Hist.," (3), vii. (1861), pp. 114-5 ; 

 " Zoologist," xix. (1861), p. 7355 ; "Ann. and Mag. Nat. Hist.," (3), 

 ix. (1862), p. 186; J. G.Jeffreys, "British Conchology," i. (1862), 

 p. 100; A. H. Cooke, "Journ. of Conch.," iii. (1882), p. 2>^'ii; 

 T. D. A. Cockerell, "Zoologist," (3), ix. (1885), p. 14 ; A. J. Jenkins, 

 "Journ. of Conch.," vi. (1890), pp. 270-1 ; W. D. Rae, " Science 

 Gossip," xxvii. (1891), pp. 89-90. 



