THE CARNIVOROUS SLUGS OF SOUTH AFRICA. 187 



the left side of the rectum and even beyond the anus (PI. X 

 fig. 33). The walls of the kidney are very much folded 

 internally (see especially PI. XI, fig. 35), and ai-e lined by an 

 epithelium consisting of glandular excretory cells with 

 conspicuous round nuclei (PI. XXII, fig. 141). 



The reno-pericardial duct is very narrow, but projects 

 some distance into the kidney. Its position is shown in 

 PI. XI, fig. 35. The epithelial cells lining the duct are 

 provided with veiy long cilia. 



The kidney communicates with the ureter by a minute 

 pore situated in the centre of a slightly raised papilla at the 

 right end of its dorsal extension (PI. XII^ fig. 36). The 

 ureter, as in other sigmurethrous Stylommatophora, is 

 doubled back upon the kidney, and curves round its inner 

 posterior side. Ventrally it is continued backwards beside 

 the ventral prolongation of the kidney, and extends to the 

 extreme end of the mantle-cavity, where it bends abruptly 

 upwards and opens. The ureter is lined by a cubical 

 epithelium, the appearance of which is shown in PI. XXII, 

 fig. 141. This epithelium becomes thinner over the papilla in 

 which the opening of the kidney is situated ; elsewhere it is 

 remarkably like the epithelium which lines the lower surface 

 of the shell-sac. 



As in Testacella and the Rhytidid£e, there is no 

 secondary ureter; but a rather irregular groove runs for- 

 wards from the opening of the ureter along the roof of the 

 mantle-cavity. This groove reaches nearly to the point 

 where the ureter begins, and then bends round and runs 

 obliquely backwards and to the right, to end in the cleft in 

 the inner lip of the respiratory opening. The epithelium 

 lining this groove is similar to that lining the ureter itself, 

 and the groove is probably to be regarded as an incipient 

 secondary ureter, such as is found in many other forms. 

 The somewhat peculiar course of the groove might be 

 explained on the assumption that the respiratory orifice 

 was originally situated further forwards. 



VOL. 3, PAKT 2. 14 



