18 INTRODUCTION. 



acquainted with it. The contrary, however, appears 

 to be the fact. M. de Ferussac, who,* from his 

 extensive correspondence, might have been expected 

 to possess the best information on the subject, gave 

 Mr. Alder a variety of C. cornea (frequently found 

 in this country), as the supposed C. lacustris Drap. 

 This, though slightly rhomboidal in outline, does not 

 agree very well with Draparnaud's description. Mr. 

 Clark has a shell obtained in Devonshire, which 

 comes nearer to it. 



The following introduced species are only found in 

 tropical climates : 



1. ACHATINA octona Turton Man. ed. 1. f. 72. 

 Cionella elongata Jeffreys, Linn. Trans, xiii. 349. 

 Bulimus octonus Brug. E. M., Chemn. ix. f. 



1264. 



Inhab. the West Indies, St. Vincent's. 



Placed in the list by Dr. Pulteney, probably by 

 mistake for Lymneus glaber. Mr. Jeffreys (Linn. 

 Trans, xvi. 349.) believed he had rediscovered this 

 tropical species, but at length gave it up. Mon- 

 tagu doubted its being British. (T. B. 307.) 



2. BULIMUS exilis Deshayes. f. 109. 

 Bulimus guadalupensis Brug., Lam. 

 Helix acuta Chemn. ix. f. 1124. 

 Helix guadalupensis Dillw., Ferussac. 

 Bulimus antiguensis Guild. MSS. 

 Helix detritus Montag. T. B. 



Lymneus detritus Turton, Man. ed. 1. f. 109. 

 Bulimulus trifasciatus Leach, Zool. Misc. 

 Bulimulus acutus Leach MSS. 

 Helix exilis Gmel, Lister, C. t. 8. f. 1. 



