DISPERSAL BY MAN. 235 



it is certain that the contrary cannot now be positively 

 asserted ; we are unable to distinguish our native 

 fauna with any degree of certainty/ A few notes on the 

 species in question, beginning with the famous and much 

 discussed edible or Roman snail may be given. 



Helix POMATIA L. Merret and Lister, two very 

 early writers on the British fauna, do not seem to have 

 doubted the indigenousness of the edible snail to this 

 country ; the first-named author in his " Pinax," pub- 

 lished in 1667, mentioned the animal (according to 

 Gray) without any note, as found in Sussex ; and Lister 

 in his " Historiae Animalium Angliae," dated in 1678, 

 mentioned it, as " Cochlea cinerea, maxima, edulis, etc.,'' 

 as one of the largest of the land-shells of our island, 

 and, as far as I am aware, he never suggested that it 

 might have been imported ; it was plentiful, he said, in 

 Hertford and other places in the south of England, but 

 he had never found it in the north. Ninety-nine years 

 later, strangely enough, we find Pennant (in 1777) 

 naming the species "exotic," and stating that it had 

 become naturalized in the southern counties, having been 

 introduced, it was believed, by the eccentric Sir Kenelm 

 Digby, either for medical purposes or as a food; ''tra- 

 dition says that to cure his beloved wife of a decay 

 was the object." In 1778, Emanuel Mendes da Costa 

 named the creature " Italian," and gave a curious and 

 interesting dissertation as to its introduction and subse- 

 quent dispersal : 



> See Rimmer's '' Land and Fresh-water Shells," (1880), p. 145- 



