The Non-Marine Mollusca of Portuguese East Africa. 127 



Gudeella mixta (Smith), 1S99. 



1899. Thapsia mixta Smith, P.Z.S., p. 582, pi. 33, figs. 13-15. D.F. 



Hah. L. Marques. Macequece District ; Donclo ; Mtisherra E. Valley ; 

 Zangwe Basin (Cressy) ; Maforga Siding (Mcdowell). 



Described from Mt. Chiradzulu, this widely distributed species appears 

 to extend northwards to Kenya, where it has been collected by Kemp at 

 Riimruti, and westwards to the Belgian Congo, whence I can find no valid 

 grounds for separating from it shells collected by Dyke at Boteke and 

 Leverville. 



While very constant in form, it varies considerably in colour, which 



Text-fig. 5. — Gudeella mixta (Smith), Macequece. 



A. Roof of mantle-cavity seen from the outside, showing kidney, etc. (slightly diagram- 



matic) ; X 8. 



B. Representative teeth from the radula ; X 600. 



C. Hind end of foot seen from the left side ; X 10. 



D. Mantle-edge seen from the front, showing pallial lobes ; X 13. 



may be lacteous, corneous, or even bicoloured, and in the strength of its 

 spiral sculpture on both sides, but every intermediate grade seems to exist, 

 so that it is inadvisable to attempt separation. Zonitoides cupido M. and P. 

 appears identical with Smith's species and will probably have to be placed 

 in synonymy. 



The foot of the animal of mixta (text-fig. 5, C) is narrow, and ends 

 posteriorly in a pointed lobe, overhanging the caudal mucous gland, which 

 opens by a vertical slit. Peripodial grooves cut off a rather broad foot- 

 fringe, and the sole is tripartite. 



The mantle-edge (text-fig. 5, D) bears a couple of somewhat pointed shell- 

 lobes. The right one is rather narrow, and nearly 1 mm. long in a dead, 

 contracted animal ; the left is smaller, and somewhat triangular in form. 



