THE SLUGS OF NATAL. 169 



Distribution. 



With the exception of one species, A. purcelli Cllge., all 

 the species are confined to Natal and Zululand. 



Affinities and Systematic Position. 



When examining the internal structure of the genus 

 Apera, I have more than once been struck with what I 

 believe to be cases of morphological modification coupled 

 with degeneration, and these points must be carefully borne 

 in mind when attempting to define the systematic position 

 and affinities of tins genus. 



Hitherto the genus has been regarded as a member of the 

 Testacellida3, but the unsatisfactory assemblage of molluscs 

 which have there been included demand a careful examina- 

 tion before we assent to place the genus under discussion 

 therein . 



The Sarasins (22) in their beautiful work on the land 

 mollusca of the Celebes, expressed the opinion that Apera 

 was an ancestral fonn of Atopos Simr} The late Dr. 

 Heynemann (in litt, 1903) wrote me — ''It seems to me that 

 the Sarasins are in the wrong," and I fully agree Avith that 

 view. 



In my opinion there are no grounds, beyond a very faint 

 superficial resemblance, for regarding it as in any way related 

 to the genus Atopos Simr., or any of the Rathouisiidas. 



All the Testacellid characters can be accounted for quite 

 apart from any phylogenetic affinity with the genus Testa- 

 cella Cuvier, thus affording another instance of parallel 

 evolution which is so admirably illustrated by numerous 

 diverse families of pulmonate gastropoda. 



Whether or not the genus Schizoglossa of Hedley bears 

 any relationship to Apera I very much doubt; from what 

 little we know of the internal structure I should be inclined 

 to regard it as belonging to the Testacellid a3. 



' For an account of this genus and its affinities see Collinge. ' Jouni. 

 Malacology,' 1902, vol. ix, p. 86. 



