204 



Transactions of the Royal Society of South Africa. 



species bears a close resemblance to that foiincl in Pomatias elegants (Miill.), 

 as described and figured by de Lacaze-Duthiers,* Garnault,f and others. 

 The cerebral ganglia are situated just behind the convoluted salivary 

 glands, and are joined by a commissure which is slightly shorter than the 

 breadth of each ganglion. The buccal ganglia occur farther forwards on 

 the buccal mass, but behind the opening of the oesophagus. The cerebro- 

 buccal connectives and the buccal commissure are very slender. The 

 right pleural ganglion is close to the right cerebral ganglion, but the left is 

 lower down, the left cerebro-pleural connective being about twice as long 

 as the right. The left pallial nerve arises from the left pleural ganglion, 

 but the right pallial nerve arises from the right pleuro-pedal connective 

 close to its union with the right pedal ganglion. Dialyneurous connections 



Text-fig. 27. — Tropidophora (Ligatella) insularis (?) (Pfr.), Macequece. 

 Representative teeth from the radula ; X 150. 



appear to occur between the pallial nerves on each side and the supra- 

 intestinal and sub-intestinal ganglia, but they are so slender as to be difficult 

 to trace. The rounded pedal ganglia are partly covered by the muscles of 

 the foot. The crossed visceral loop is of considerable length. The 

 abdominal nerve-centre comprises two separate ganglia, the right one of 

 which is the larger and sometimes appears to be double. 



Digestive system.— The radula (text-fig. 27) is about 6f mm. long, and 

 has 230 transverse rows of teeth. The central teeth are usually furnished 

 with five short cusps, of which the middle one is the largest. Some of the 

 central teeth, however, have six cusps, one of the small outer cusps being 

 divided into two. The first lateral teeth have five or six cusps, the third 

 from the inner edge being much the' largest. The second lateral teeth 

 usually have six or seven rather narrower cusps, and some of them have as 

 many as eight. The marginal teeth are much broader, and may have been 

 formed originally by the union of several narrower teeth similar to those 

 found in the Rhipidoglossa. They may be divided into three portions : 



* Arch. Zool. Exper., vol. i, 1872, pi. iii, fig. 8. 

 t Actes Soc. Lin. Bordeaux, 1887, vol. xli, pi. i. 



