56 PROCKEDINGS OK THE MALACOLOGICAL SOCIETY. 



that I have seen took the form of accessory endocones to central tooth ; 

 central and first lateral fused; second lateral with bifid endocones. 

 In two specimens the marginals were much shorter than those figured, 

 and lay huddled together much after the fashion of those of the 

 genuine nitidula. 



In conclusion, I believe that the great variation in genitalia and 

 radulse which has been observed within the limits of certain species 

 is due largely to the fact that the species hitherto recognised have 

 been composite. But, if I may borrow a phrase now consecrated by 



Seal£ of tenths of a millimetre 



Fig. 4. 



official usage, there is such a thing as non-significant variation. Some 

 instances of it have been noted above ; but it is only by obtaining 

 a more complete knowledge of the physiology of the snail that we can 

 hope to settle definitely what variations come under this head. One 

 other thing : the Vitrea radula has larger teeth than that of any other 

 group except Testacella ; but to see even Vitrea properly a really high 

 power is needed. 



