DISPERSAL BY MAN. I93 



seems to have been exceptionally severe.^ The suc- 

 cessful transportal of Helix nevioralis from England 

 to New Jersey, and the establishment of several new 

 colonies of the same species from an accidentally intro- 

 duced stock in Virginia, have just been mentioned ; 

 Helix appressa, sent from Illinois, became well estab- 

 lished in New Jersey in the same garden ; " Helix 

 austriaca^ according to a statement in the Zoological 

 Record ior 1871,^" acclimatized seventeen years ago 

 near Stettin, thrives there very well and multiplies 

 considerably ; " Helix villosa from Switzerland turned 

 out by the Rev. Canon Tristram on a moor in 

 CO. Durham was known to be living in the same place 

 ten years later, and Helix lapicida from the south 

 of England planted by one of Mr. Tristram's friends 

 on some rocks on the banks of the Wear, in the same 

 county, ultimately became one of the recognized 

 local shells. But Claiisilice from Africa and from 

 Syria and various species of Helix from the latter 

 region also turned out in the same county, being 

 able to " protect themselves against heat better than 

 cold," are said to have perished during the first 

 winter ; "^ Helix lapicida from England, and Bulimus 

 decollatus from Charleston, South Carolina, disappeared 



\ G. Norman, "Zoologist," xii. (1854), p. 4435. 



2 W. G. Binney, "Terrestrial air-breathing Mollusks," v. (1878), 

 pp. 29, 306. 



^ viii. (1871), p. 130, referring to Dohrn, " Nachr. malak. Ges.," 

 iii. pp. 17-18. 



4 H, B. Tristram, " Zoologist," (3), i. (1877), pp. 260-1. 



O 



