134 Transactions of the Royal Society of South Africa. 



mesocones. The basal plates of these teeth have the usual somewhat 

 quadrate form. The margiual teeth are more than three times as numerous 

 as the laterals, and gradually decrease in size towards the edges of the 

 radula. They have narrow basal plates, and strongly curved bifid cusps, 

 formed of the mesocones and the somewhat shorter ectocones. The rows 

 of teeth trend slightly forwards on each side of the middle line. The radular 

 formula of the specimen figured is : (42+ll + l+ll + 40)X 148. That of 

 another example is : (35+ll + l + ll + 36)X 135. 



Semper's figure shows no endocones on the lateral teeth, and not even 

 an ectocone on the tenth tooth, which may have been abnormal in the 

 radula that he examined. He does not depict the marginal teeth, but 

 states that they have typical bifid cusps. Godwin-Austen also shows no 

 endocones on the lateral teeth, which he depicts as smaller than the central 

 tooth and far narrower than they are in the specimens from the Lebombo 

 Mountains. Moreover, he figures the marginal teeth as having very much 

 smaller ectocones. If Godwin-Austen's figures are accurate there can be 

 little doubt that the form he studied is specifically distinct from the one 

 now described. 



The crop is narrow, and the salivary glands are united above it. 



Free retractor muscles. — The columellar muscle divides almost at its 

 origin into four main branches : a powerful buccal retractor, which lies 

 above the other muscles and is bifurcated in front ; the right and left 

 tentacular retractors, each of which gives off a stout branch to the anterior 

 end of the foot before dividing into the retractors of the upper and lower 

 tentacles ; and a broad ventral muscle to the posterior part of the foot. 

 The retractor of the right upper tentacle passes between the vagina and the 

 penis. The penial retractor arises from the posterior end of the diaphragm, 

 and is inserted in the epiphallus. 



Reproductive system (PI. VIII, fig. 3). — The hermaphrodite gland is em- 

 bedded in the posterior division of the liver. The hermaphrodite duct is less 

 swollen and convoluted than is often the case ; it bears a small oval vesicula 

 seminalis at its junction with the albumen gland. The common duct is of the 

 usual form, as may be seen from the figure. The free oviduct is of moderate 

 length, longer than in Godwin-Austen's figure ; the vagina is short ; and 

 both are rather narrow. The genital atrium is small, and no dart-sac is 

 present. The receptacular duct has muscular walls and is nearly twice the 

 length of the free oviduct ; posteriorly it merges gradually into the club- 

 shaped receptaculum seminis or spermatheca, which has much thinner walls 

 and lies against the common duct. Semper's figure shows an oval sper- 

 matheca, with a longer and more slender duct, swollen at its junction with 

 the vagina. Godwin-Austen shows an organ a little less unlike that just 

 described. 



