THE CARNIVOROUS SLUGS OF SOUTH AFRICA. 239 



suppose that anyone would maintain that all the carnivorous 

 snails and slugs, including" such genera as Atopus and 

 Varicella, had been derived from this source. 



But while I agree that Daudebardia has probably arisen 

 from the Zonitidse, I canuot admit that Testacella is 

 closely allied to Daudebardia and has had a similar origin. 



Testacella differs widely from Daudebardia in many 

 respects. In Testacella the apex of the shell is directed 

 backwards, the columella being parallel to its greatest length 

 (PI. XXIV, fig. 161) ; in Daudebardia the columella is 

 nearly at right angles to the length of the animal and the major 

 diameter of the shell, as in Hyalinia. In Testacella the 

 pedal gland lies freely in the body-cavity, and is very different 

 in structure from that of most snails and slugs, a fact that has 

 been specially emphasized by Andre ^; in Daudebardia the 

 pedal gland is embedded in the foot, and Plate- has shown 

 that it has the usual structure, the duct having two ventral 

 longitudinal folds enclosing a furrow into which the gland- cells 

 open. In Testacella the epidermal cells have their walls 

 thickened on the outer side only; in Daudebardia they are 

 thickened all round. ^ Testacella has no jaw; in Daude- 

 bardia a jaw is present. In Testacella the radula-sac does 

 not extend nearly to the hind end of the odontophore (PI. XXIV, 

 fig. 156) ; in Daudebardia it projects beyond the odonto- 

 phoral muscles. In Testacella the visceral ganglia are all 

 separate from one another; in Daudebardia the abdominal 

 ganglion is united with the right parietal ganglion, as is the 

 case to some extent in Hyalinia also. In Testacella the 

 auricle is behind the ventricle ; in Daudebardia the auricle 

 is in front of the ventricle, as in Hyalinia. In Testacella 

 the heart is to the right of the kidney ; in Daudebardia and 

 Hyalinia it is to the left. Testacella has no secondary 

 ureter; Daudebardia agrees with Hyalinia in possessing 

 one. In Testacella the receptacular duct is moderately long; 



' ' Revvie Suisse de Zoologie/ 1894, vol. ii, pp. 318-321. 

 - ' Zool. Jahrb.,' 1891, vol. iv, p. 524, pi. xxxii, fig. 16. 

 =* Ibid.,pp. 527, 529. 



