THE TANGANYIKA PROBLEM. 
27 3 
sion of crystalline styles. They are probably correctly 
regarded as a group of rather primitive Cerithoids, which 
anteceded both the Amarula type of Melanias and the 
Diagram to show the modifications witnessed in the reproductive apparatus in a number 
of divergent gasteropods. g.g, Genital gland. V.D , Yas differens. O.D, Oviduct. 
G. V, Genital groove. V.D, Enclosed portion of vas differens. b.p , Brood pouch. 
p. Penis. h.g. Hermaphrodite gland. h.d. Hermaphrodite duct. V.S, Seminal 
vesicle, e.p, Evertable penis. 
modern Ceriths, which are found now inhabiting the 
seas. 
Tanganyicia is much more difficult to place ; it possesses 
18 
