114 HUGH WATSON. 



and it is largely a stoiy of mistakes. It will have been seen 

 that four species have been described, three from Natal and 

 one from the Cape, but that very little is known about the 

 anatomy of any of these, as only two reliable figures have 

 hitherto been published of their internal features, namely, 

 Binney's figure of the radula of A per a gibbon si, and 

 Collinge's second figure of the reproductive organs of the 

 species which he supposed to be A. burnupi. Nevertheless 

 this ignorance does not seem to have prevented malacologists 

 from speculating about the affinities of the genus ; for, as we 

 have seen, it has been suggested in turn that it may be related 

 to the Test ac ell idte, to the Janellidi^, to A top us, or to 

 the Rhytididge, forms which differ immensely from one 

 another. It is hoped that the information contained in the 

 present article may give greater value to such speculations in 

 the future. 



In the following pages I am attempting to describe this 

 remarkable genus in as great detail as the limited number of 

 specimens at my disposal will permit, giving numerous figures 

 of its anatomy. Secondly, I am giving a concise description 

 of the distinctive characters — both external and internal — of 

 each species; that is to say, of Apera gibbonsi, A. pur- 

 celli, A. burnupi, the species that Collinge erroneously 

 supposed to be A. burnupi, which I am naming A. sex- 

 angula, and two new species — A. dimidia from Natal, and 

 A. parva from Gi'ahamstown. And at the same time I am 

 pointing out that there are some very distinct races of A. 

 gibbonsi, which may also prove to be separate species, but 

 which I am ])rovisionally regarding as sub-species until more 

 material is obtainable. After dealing with the relation of 

 these forms to one another, I am describing briefly the species 

 of Test ace 11 a that occurs at the Cape, and am then dis- 

 cussing at some length the probable relations of Apera and 

 Testacella to each other and to the remaining genera of 

 carnivorous snails and slug's. 



