DISPERSAL BY MAN. 1 85 



lata, Planorbis car hiatus , P. complanatus^ P. corneus, L. 

 stagnalis, and L. glabra, from localities, likely to be de- 

 stroyed, \\\ the neighbourhood of Manchester, deposited 

 by Mr. Heathcote in quiet ponds about Farrington, 

 were stated in 1887 to be increasing rapidly in their 

 new homes. ^ A good deal of colonization from pond 

 to pond and from a distance, Mr. R. D. Darbishire states, 

 used to be practised in the neighbourhood of Man- 

 chester; PL corneus, for instance, believed to have been 

 absent from the district in i84i,'*is now common in 

 the canal at Gorton — most likely a dealer's colony ;" in 

 1844-6, it is said, " there was a great rush to Southport " 

 for Paludina contecta which was colonized by collectors 

 and dealers in canals near Manchester, at Twenty Pits, 

 Greenheys, and cotton pits, Chorlton ; P. vivipara, 

 also, at Birch, is regarded as a probable introduction.^ 

 On the other hand, L. stagnalis, put down by Mr. W. 

 Baillie in a stream near Brora, Sutherlandshire, probably 

 " picked by birds/' could never afterwards be found ; ^ 

 5. corjieum, B. tentaculata, and L. stagnalis, introduced 

 into a dam near Greenock, seemed to have died out by 

 the following year ; ^ and of several living specimens of 

 L. stagiialis and PL corneus, placed in a small pond on 



* R. Standen, " Nat.," 1887, p, 176. 



- R. D. Darbishire, cited by Mr. Standen, "Nat.," 1887, pp. 160 

 and 164. 



^ Neritina fluviatilis, B. tentaciilata^ and PI. complaiiatics have 

 also been planted in small numbers by Mr. Baillie in the neigh- 

 bourhood of Brora. 



^ T. Scott, "Trans. Nat. Hist. Soc. Glasgow," (n. s.), i. (1887), 

 p. 282. 



