108 HUGH WATSON. 



PAGE 



Apera parva n. sp. . . . . . 202 



Apei'a dimidia n. sp. . . . . 204 



Apera piircelli CoUinge .... 207 



Ajjera bui-nupi Smith . .210 



Apera sexangula n. sp. .... 213 



The Phylogeny op the Species of Apera . . 217 



The Occurrence at Cape Town of Testacella maugei 



F<'r. . ■ .220 



The Affinities of Apera and Test.4CELLA . . 222 



The Evolution of Carnivorous Characters . . . 222 



The Phylogeny of Apera and other naked Carnivorous Slugs 231 

 The Phylogeny of Testacella and its possible Allies . 238 



Appendix — Bibliography of Testacella maugei Ft'r. . 256 



Explanation ok Plates ..... 258 



INTRODUCTION. 



Many snails and slugs of great interest inhabit South 

 Africa, but very little is known about their anatomy. I have 

 therefore been asked to describe some of these animals, 

 beginning with those in which the shell is degenerate or 

 absent. The present article deals with the slugs belonging to 

 the carnivorous gi'oup, and principally with those contained 

 in the genus Apera ; and as this genus is a very remarkable 

 one and seems to be confined to South Africa, I am endeavour- 

 ing to describe it in some detail. Unfortunately, however, 

 the material at uiy disposal has been limited to a small 

 number of pi-eserved specimens, some of which have proved 

 to be immature. More than half of these specimens were 

 collected and sent to me by Mr. H. C. Bnruup, of Pieter- 

 maritzburg, to whom I am very deeply indebted. I am also 

 glad to have this opportunity of expressing my thanks to the 

 Rev. Prof. H. M. Gwatkin, to Dr. Doncaster of Cambridge, 

 Dr. Peringuey of Cape Town, Dr. Pilsbry of Philadelphia, 

 Dr. Simroth of Leipzig, and Dr. Warren of Pietermaritzburg, 

 to Major M. Connolly, and to Messrs. Keppel H. Barnard, 

 Walter E. Collinge, John Farquhar, John H. Ponsonby, (1. C. 

 Robson, Edgar A. Smith, and William Tains. 



