THE TANGANYIKA PRO B J JIM. 



223 



on what we now know about the prosobranchiate mollusca 

 in general. 



TYPHOBIA, SMITH. T. IIOREI (FIG. 2). 



The genus TypJiobia is represented solely by the unique 

 form T. horei which occurs generally in the deep water of 

 Tanganyika, in a hundred fathoms and upwards, and on 

 the muddy portions of the floor of the lake. The animal 

 which is of considerable size possesses the remarkable shell 

 represented on page 221, and the conchological characters 



Fig. 4. — Lingual dentition of Typkobia horei. A single row of the teeth on 

 the left side. ( X 150.) 



which different individuals display may vary widely. 

 Typkobia, like all the remaining halolimnic gastropods 

 is prosobranchiate, and the mantle cavity presents the 

 same arrangement of the parts which is usually found in 

 the less specialised Taenioglossa, Aporrhais for example. 

 There is one gill (Stenidium) composed of simple triangular 

 leaves and below this a long rope-like osphradium (Fig. 3). 

 The renal aperture is at the extreme upper end of the 

 mantle cavity, and the intestinal and reproductive apertures 

 open on the right, and on the extreme front of the mantle 



