THE CARNIVOROUS SLUGS OF SOUTH AFRICA. 245 



left of the heart. Turning now to the Oleacinidge, we find 

 that in Euglandina, Sti'eptostyla, etc., the heart already 

 occupies a position similar to that which it holds in Apera, 

 as is evident from diagram c' This is probably due partly 

 to the pushing forwards of the ventricle owing to the pressui'e 

 of the hinder portion of the odontophore/ and partly to the 

 shape and consequent orientation of the shell.^ Diagram E 

 shows the position of the heart and kidney in Strebelia, so 

 far as I can judge from Strebel's figures, and it Avill be seen 

 that with the reduction in the size of the shell and its retro- 

 gression to the hind end of the animal, the heart has I'otated 

 a little further. It is but a short step from this to the con- 

 dition shown in diagram F, which illustrates the position of 

 the heart in Testacella, Avitli the auricle directly behind the 

 ventricle. Sixty 3' ears ago Reymond expressed the opinion 

 that Testacella was "a Glandina with a rudimentary 

 shell," and if we substitute the word " vestigial " for " rudi- 

 mentary," I believe tliat Reymond expressed the truth. 



At the same time I am aware that the most eminent modern 

 authorities have expressed a contrary opinion. Dr. Pilsbry ■* 

 states emphatically that the relationships of the European 

 carnivorous slugs (including Testacella) are with the 

 Aulacopoda, and not with the other carnivorous families; 

 and Simroth entertains the same view. The only facts which 

 Pilsbry brings forward in support of this hypothesis are 

 (1) that the European carnivorous slugs have lateral and 

 pedal grooves, which he states that the other families do not 

 possess, and (2) that the cerebral ganglia are generally united 

 by a rather long commissure in the European slugs, while in 

 the other families the cerebral ganglia are in close contact. 

 Let us examine these points. 



In the first place, lateral grooves occur not only in Testa- 



' See also Strebel, op. cit.. vol. iii, pi. v, fig. 5. 



See p. 229. 

 ^ Cf. Naef, A., ' Ergebn. d. Fortschr. d. Zool.,' 1911, vol. iii, p. 131, 

 fig. 19. 



^ ■ Manual of Conch.' (2nd ser.), 1908, vol. xix, p. viii. 



