CONCHOLOGY. 



cimens of the late Leverian Museum, and presumed to be the 

 largest and most perfect known. 



For the discovery of those fine varieties of Helix perversa, the 

 naturalist is indebted, as in many other instances, to the assiduous 

 attention of Sir Joseph Banks, by whom they were brought from 

 Prince's Island, in the Pacific Ocean. The circumstance that intro- 

 duced them to his notice deserves mention. During the voyage of 

 discovery, made by Captain Cook in those seas, in which he was ac- 

 companied by that eminent naturalist and his scientific friends, the 

 expedition touched at Prince's Island, and a party of sailors was 

 sent ashore in search of water and to cut timber. Thus employed 

 they felled a number of the loftiest trees, and upon the uppermost 

 branches of those trees, when brought to the earth, this species was 

 found crawling like other snails among the foliage. Sir Joseph Banks 

 being present, was thus enabled to select the shells from those other- 

 wise inaccessible branches at his pleasure, and as the foliage afforded 

 every variety of those shells, he was happily enabled to form a choice 

 assortment of the whole. This peculiarity of the species, living 

 upon the upper branches of the highest trees only, may pos- 

 sibly explain the cause of the present rarity of those shells, even 

 should the Island be occasionally visited by our navigators. All 

 the specimens known among collectors, so far as we can learn, are 

 those which were found at that time by Sir Joseph Banks, and dis- 

 tributed among his friends in England upon his return. 



Mr. Diilwyn observes that Linnaeus considered the Helix 

 Perversa as a river shell ; Linnaeus was certainly so far mistaken, he 

 says nothing of its habitat in describing the shells in the cabinet of 

 the Queen of Sweden, but in the 12th edition of Systema Naturae we 



