THE TANGANYIKA PROBLEM , . 
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evidently functioned as a brood pouch. The buccal mass 
is very much reduced in Tang any icia , appearing only as 
a slight dilation of the alimentary tube, and the tongue 
and the teeth (Fig. 32) are both proportionately small, 
the denticles having the characters represented in Fig. 31. 
The nervous system (Fig. 31), the ganglia, their cords 
Fig. 32. — Semi diagram of the digestive 
system of Tanganyicia rufofilosa. 
and connectives, are all arranged in the typical cerithoid 
plan, just as in Typhobia or Cancellana. But there 
is in the brain of Tanganyicia a curious median lobe 
situated between the cerebral ganglia and looking forward, 
which I have never found elsewhere. Except for the 
addition of the large rectal gland in the female Tanganyicia , 
and the reduction of the buccal mass in both sexes, the 
whole alimentary canal (Fig. 32) is built on precisely the 
