BULIMUS. 239 



The first of these curious resemblances may be caused 

 by the adhesion of Lichen spores, which would grow as 

 well upon a shell as upon the bark of a tree ; and the 

 other cases I have endeavoured to explain. B. obscurus 

 is sometimes found at considerable heights, probably 

 indicating its Arctic origin. M. Puton observed it on 

 the Vosges mountains, at an elevation of 2624 feet above 

 the level of the sea. It occasionally occurs on granite 

 and gneiss, but more commonly on calcareous strata. 



The difference, which is slight, between this species 

 and B. montanus will appear from the description. The 

 simplest character is that the latter is at least four times 

 the size of the other in cubical contents. Lister seems 

 to have been acquainted with the present species ; but 

 his notice of it is not satisfactory. In its young state 

 it is in all probability the Helix trochulus of Miiller. 



The Helix detrita of Montagu (judging from a speci- 

 men received from him by Mr. Dillwyn and now in my 

 collection) is exotic, and apparently a variety of the 

 Bulimus Guadaloupensis of Bruguiere. 



The B. tuberculatus of Turton (the typical specimen 

 of which I also have) is the Helix pupa of Linne*. It is 

 a native of the extreme South of Europe, and is not at 

 all likely to have been found in Worcestershire, whence 

 Dr. Turton is said to have received it. Capt. Blomer, 

 who gave this specimen to Turton, told me that he had 

 been in Sicily; and he admitted that he might have 

 made a mistake as to the locality. 



The Helix Goodallii of Miller is a West-Indian species, 

 and appears to have been introduced into this country 

 with pine-plants. It is still very common on the tan in 

 the pineries at Garraway and Go's, nursery-gardens 

 near Bristol, where the late Mr. Miller first observed 

 this little shell about forty years ago. It has not been 



