THE TANGANYIKA PROBLEM. 247 
spermatic groove (Fig. 29) running from the opening of 
the genital duct along the body and on to the foot below 
Fig. 29. — Semi diagram of the anatomy of Tanganyicia ntfofilosa. 
The mantle opened from above, and the nerves in black ; 
cryst. s., crystalline style ; sL, stomach ; b. p., brood pouch. 
the tentacles on the right side, just as it does in Strombus, 
Pteroceras, or Littorina. In the female Tanganyicia this 
genital groove is also present, and leads from the genital 
