THE CARNIVOROUS SLUGS OF SOUTH AFRICA. 171 



and backwards from the sides of the roof of the odontophore 

 to the support, parallel to the lateral retractors ; further 

 back, however, they are either absent or completel}' fused with 

 the lateral retractors. Taking into consideration the similarity 

 of the radula of Testacella to that of Apera, it is surpris- 

 ing that there should be so many diiferences in the muscles 

 which control its movements. 



In the Oleacinidas the odontophore resembles that of 

 Testacella in some of its features, and that of Natalina in 

 others, although it often possesses more primitive characters 

 than can be found in either of these genera. StrebeP has 

 given a detailed account of the odontophore of Euglandina 

 sowerbyana (Pfr.), from which it will be seen that in this 

 species the median retractors enclose the hind end of the 

 radula-sac and become continuous posteriorly with the 

 extrinsic buccal retractor. In this respect, therefore, Eug- 

 landina sowerbyana resembles Testacella. But this 

 is not the case with many of the other forms, such as fj . 

 venezuelensis {Preston) or Streptostyla shuttle- 

 worthi {Pfr.)," for in these the radula-sac is long, and its 

 posterior part has not yet become entirely surrounded with 

 muscles, but projects slightly from the hind end of the odonto- 

 phore. In most genera the posterior end of the odontophore 

 is curved downwards as in Natalina. The median dorsal 

 muscle resembles that of Apera, and the ventral muscles are 

 also like those of Apera and Natalina. On the other hand, 

 the suspensor muscles are like those of Testacella, and I 

 found that Euglandina venezuelensis also resembled that 

 genus in having the retractors fused with the sheath of the 

 odontophore towards the hind end. No median ridge or 

 furrow occurs along the inner surface of the support in 

 E. venezuelensis, and I did not find any flexor muscles 

 along its edges. Possibly the longitudinal muscle-fibres 

 within the support take the place m Testacella and 



' ' Beitrag z. Kenntniss d. Fauna Mexikanischer L. u. Siisswasser- 

 Conchylien,' 1878, vol. iii, pp. 40-42, pis. xvii, xviii. 

 - Strebel, op. cit., pi. v, fig. 7a. 

 VOL. 3, PART 2. 13 



