260 



THE TANGANYIKA PROBLEM. 



proceeded less in Spekia than in any of the forms which 

 Haller figured 



The gill in S. zonata is very much like that of the genus 



cryst. s. 



Fig. 43. — Semi diagram of the anatomy of Spekia zonata. 

 The mantle cavity has been opened from above, and the 

 nerves are represented in black. Opposite st the stomach ; 

 stn. the gill ; cryst. s. the crystalline style. 



Tanganyicia. The leaves are similarly broad, low, and 

 triangular, and their apices are prolonged into the same 

 littorinoid finger-like processes. 



Such processes are figured by Haller in the gills of 



