Notes on South African Non-marine Mollusca. 181 



Type-set, although the sculpture is not quite so fine, and the peristome 

 shows a tendency to coalesce with the last whorl instead of being 

 perfectly solute. 



Since the foregoing was written two bleached examples have been 

 received by the South African Museum from Bulls Mouth Pass 

 (Bullspoort) between Nauchas and Maltahohe, which undoubtedly 

 belong to the new variety. They differ slightly therefrom, however, 

 in that their sculpture is less pronounced than in the Type ; their 

 apertm-e also is more remote from the umbilicus, so that a consider- 

 able expanse of the base of the last whoi'ls is exposed between the 

 umbilicus and the refiexed edge of the peristome. 



The shells measure respectively : 



Diam. maj. 33'2, min. 26'0 ; alt, 17'0; apert. 17'9 x 147 mm. 

 31-5, 24-8 ; 16-5 ; 16-0 x 12-0 mm. 



V. On the introduced Land-Moll uscan Fauna of South Africa. 



I have more than once been taken to task for inserting the 

 introduced species in my Revised Reference List, iii their natural 

 order instead of sequestrating them to some other portion of the 

 volume. 



My answer is that not only is it almost impossible to decide, in 

 some instances, whether a species is indigenous or otherwise, but also 

 that I have been often misled, in books where the last-mentioned system 

 prevails, by not noticing or by being unable to find the introduced 

 species ; so that I much prefer including them in Generic sequence in 

 the body of the work. 



As time goes on, however, it will become increasingly difficult to 

 determine the introduced species, so it may be well to publish a 

 tentative list while it is still possible to collect information from 

 living authorities as to the dates and means of their introduction. 



This list combines two distinct groups. One contains, for the most 

 part, large forms whose importation by human agency can be actually 

 verified and whose distribution is even now confined to the most 

 restricted limits of civilisation ; the other consists of minute shells, 

 found as often as not in primeval jungle, the date and means of whose 

 introduction, if they were introduced at all, is problematical, and 

 whose diffusion is probably attributable to the agency of birds and 

 winds. 



I include Land-slugs and one or two of the Limnteidte in the 

 following list, but omit semi-marine Genera such as Melampus and 



