116 Transactions oj the Royal Society of South Africa. 



for in the species of Marconia that have been examined anatomically it has 

 been found that the radula is of a somewhat specialised type, with two 

 longitudinal zones of large teeth on each side separated by a zone of smaller 

 teeth.* 



Subfamily PTYCHOTREMATINAE. 



Genus Gulella Pfeifier, 1856. 



Gulella perissodonta (Sturany), 1898. 



1898. Ennea perissodonta Stur., S.A. Moll., p. 26, pi. 1, fig. 18. D.F. 

 Hab. L. Marques. Dclagoa Bay (Penther). 



Founded on a single specimen, which is described as having 9 teeth in 

 the aperture. It is a small form, measuring 4-0 X 2-0 mm. 



Gulella enneodon Conn., 1922. 

 (Plate IV, fig. 3.) 



1922. Gulella enneadon Conn., A.M.N.H. x, p. 114. D. 



Hab. L. Marques. District N. of Macequece (Cressy). 



The type, 6-2x3-3 mm., with 7| whorls, is of intermediate and, on the 

 whole, average size and shape in a species which varies greatly in these 

 respects, for the largest example seen contains 8 whorls, is cylindrical 

 in form, and measures 8-0x3-5; apert. l-6xl-6; last whorl 4-1 mm.; 

 while a small one containing 7 whorls is truncate-ovate, and measures 

 5-8x3; apert. 1-5x1 -2 ; last whorl 3-3 mm. 



The sculpture and dentition are remarkably constant throughout a 

 large series, the nine teeth being almost invariably conspicuous, though 

 comparatively weaker in the largest examples ; I have, however, seen one 

 curious abnormality, in which the large tooth on the outer lip is single, but 

 there is a second, smaller denticle on the left of the base. 



The only close affinity of G. enneodon is with G. perissodonta, but Dr. 

 Sturany, who has kindly compared them, informs me that they are quite 

 distinct. The presence in both species of the mid-parietal denticle and the 

 two small teeth low on the outer lip draws them very near together, but the 

 sculpture of enneodon is finer, the aperture comparatively smaller, the whorls 

 more numerous and the suture less deeply incised, which, together with the 

 smaller size of perissodonta, should afford ample means of distinction 

 between them. 



* Thiele : Deutsch. Zentral-Afrika-Exped. (1907-08), vol. iii, 1912, p. 183, fig. vii 

 (Marconia latula (Marts.)) ; Pilsbry : Bull. Amer. Mus. Nat. Hist., vol. xl, 1919, pp. 172, 

 173, fig. 61 {Marconia lata ruwenzoriensis Pils.); Peile in Connolly: Ann. and Mag. Nat. 

 Hist., ser. 9, vol. x, 1922, p. 488 {Marconia margarita (Preston), a form in which the 

 outer large teeth are not quite so well developed as in the two preceding sj^ecies). 



