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West of Ireland ; but it does not appear to have been 

 detected in Scotland. Although diffused, it is local and 

 rare. It occurs in our upper tertiary strata. On the 

 Continent it ranges from Finland to the North of Italy, 

 viz. Lugano (Stabile); Como (Porro); Lombardy (Villa); 

 and Aradas and Maggiore are said to have found a 

 specimen on the sea-shore at Catania. 



This is a very shy little snail and slow in its move- 

 ments. When it is about to crawl and emerges from 

 the shell, it puts its foot foremost. Its slime is rather 

 abundant. The shell is carried perpendicularly. The 

 epiphragm is membranous and plaited. Miiller says 

 that under the microscope a small black line can with 

 great difficulty be detected in the place which is occupied 

 in the animal of Pupa by each of the lower tentacles. 



The reversed direction of the spire is an easy mark of 

 distinction between this and all the foregoing species of 

 Vertigo. The present species is not a sinistral form or 

 variety of any other kind, as I have satisfied myself by 

 comparing this in a mirror (which of course makes the 

 spire appear dextral) with V. antivertigo and V. sub- 

 striata, in which the teeth are somewhat similarly 

 arranged. The shape of the present species, if it were 

 dextral, would be intermediate between that of the last- 

 named species and V. edentula. 



Leach is the only conchologist who has proposed to 

 change the original name ; and he has rechristened this 

 species V. heterostropha. It must be recollected that 

 Miiller was the founder of the genus, as well as the dis- 

 coverer of the present species, which was at that time 

 the only one known ; so that, if any alteration were 

 necessary on account of the contrary direction of the 

 spire, this species ought at all events to retain the name 

 first given to it by its discoverer. I had long previously 



