The Non-Marine Mollusca of Portuguese East Africa. 



143 



Traclnjcystis mcdowelli Conn., 1922. 



(Plate IV, fig. 13.) 



1922. Trachycystis mcdowelli Conn., A.M.N.H. x, p. 117. D. 

 Hab. L. Marques. Maforga Siding. B. and M. Rly. (Mcdowell). 

 A particularly neat, close-coiled little species, not closely resembling any 

 known to me from Africa. 



Trachycystis rudicostata Conn., 1922. 



1922. Trachycystis rudicostata Conn., A.M.N.H. x, p. 117. D. 

 Hab. L. Marques. Mt. Vengo (Cressy). 

 Type in British Museum. 



Text-fig. 10. — Trachycystis rudicostata Conn., Dargle. 



Three individuals, measuring respectively 1-91, 2-02, and 1-8 mm. in maximum diameter, 

 the last, loM'est in text-fig., being the type. 



This species has been known for many years, and I have retained the 

 unpublished name originally suggested for it by Melvill and Ponsonby. It 

 is widely distributed throughout Natal, having been collected at Dargle 

 (type) ; Inhluzani Mountain ; Nottingham Road ; Howick ; Hilton Road ; 

 Edendale ; Pietermaritzburg ; Ntimbankulu Hill, Mid-Illovo District ; Van 

 Reenen's Pass, Drakensberg (Burnup), and Majuba (Connolly). 



Almost the only difference between it and T. lamellifera (Smith) is that 

 the latter appears to be quite destitute of the microscopic spiral striation 

 which is so prominent in rudicostata. 



The following notes on the animal are taken chiefly from specimens 



