THE CARNIVOEOUS SLUGS OF SOUTH AFRICA. 241 



just as it differs from Apera, in the pedal gland having- no 

 terminal enlargement, and in the presence of longitudinal 

 fibres in the odontophoral support and of dermal glands in the 

 foot. And if a shell of the shape of that of Paryphanta 

 degenerated, it would assume a form like that of Schizo- 

 glossa, and not like that of Testacella. Moreover, while 

 it is easy to attach too much importance to geographical 

 distribution, it does not seem probable that a w^estern Palas- 

 arctic genus of slugs should have been evolved from a snail 

 found in New Zealand. 



But is there no family of carnivorous snails inhabiting 

 Europe, in which the columella is parallel to the greatest 

 length of the shell, and the odontophoral support contains 

 longitudinal fibres? The Oleacinid^e possess these charac- 

 ters, and in many other ways bear a close resemblance to 

 Testacella, and it is from the Oleacinida? that I believe 

 Testacella has been evolved. 



Although the majority of the recent species of the Olea- 

 cinidfe are found in Central America and the West Indies, 

 in Tertiary times the family was represented by many forms 

 in Western and Central Europe, and one genus — Poire tia — 

 still lingers in the Mediterranean region. We knoAV that the 

 shell is liable to degenerate and recede to the posterior end 

 of the animal in the Oleacinidte as in other carnivorous 

 families, for it has done so in Strebelia. If the degenera- 

 tion were to proceed further than it has done in this American 

 genus, the shell would assume the form found in Testacella 

 m a u ge i . This is seen from the parallel case of the degenera- 

 tion of a shell with a pointed spire found in the Succineidffi, 

 which is well illusti-ated on plate Ixxiii of H. and A. Adams' 

 ' Genera of Kecent MoUusca.' Further, we find that the 

 abrupt truncation cf the columella which is characteristic of 

 Poiretia, Euglandina, Oleacina, etc., occurs also in 

 Testacella scutulum Soic. It is significant also that as 

 early as the Eocene period the aperture in some of the 

 European Oleaci nidge had already become as large as that 

 of any of the recent American members of the family 



