Quarterly Journal of Conchology. 131 



casual visit to Newton Abbot, I found a few specimens 

 of Clausilia Rolphii, in company with C. rugosa, C. 

 laminata, etc. under Beech and other trees by the road- 

 side a short distance from Newton Railway Station. 

 Mr. John Morley was with me at the time and I pointed 

 Rolphii out to him with the remark that I had been 

 fortunate in finding that rather rare shell in what I be- 

 lieved to be a new locality. 



Clausilia rugosa var. albida, Jeffr. During a short visit to 

 Suffolk in July, 1873, I found a single specimen of this 

 shell on a Railway arch near the village of Gislingham. 



SPECIES VERSUS VARIETIES. 

 By J. T. MARSHALL. 



In your number for August, 1875, Mr. Simpson appeals to some 

 one to "remove the difficulties which perplex his mind as to what 

 really constitutes the difference between a species and a variety, and. 

 make clear to him what is the principle upon which such differences 

 are formed." 



I will endeavour to reply to him, but fear his mind will still 

 remain perplexed, in common with all conchologists, on this often- 

 asked but unanswerable question. For if Dr. Jeffreys, after a life- 

 long and careful study of the mollusca, declares that the separation 

 of varieties from species "is often extremely perplexing," Mr. 

 Simpson cannot hope to have his mind set at rest by a discussion 

 in your columns. Long experience and acute observation will do 

 something, but even then there will always remain forms perplexing 

 to the conchologist. * 



To explain his meaning (or perplexity) Mr. Simpson cites several 

 what he calls "test cases," in which I think he is unfortunate in the 

 selection. For instance, he says he has compared Helix rufescens 

 and Helix hispida for a long time without being able to find a 



