102 



THE LAKE KEGIONS OF CENTRAL AFEICA. 



splashing the water in shovelsful over the canoe. 

 They make terribly long faces, however, they tremble 

 like dogs in a storm of sleet, and they are ready to 

 whimper when compelled by sickness or accident to sit 

 with me under the endless cold wave-bath in the hold. 

 After a few minutes of exertion, fatigued and worn, 

 they stop to quarrel, or they progress languidly till 

 recruited for another effort. When two boats are 

 together they race continually till a bump — -the signal for 

 a general grin — and the difficulty of using the entangled 

 paddles afford an excuse for a little loitering, and for the 

 loud chatter, and violent abuse, without which ap- 

 parently this people cannot hold converse. At times 

 they halt to eat, drink, and smoke : the bhang-pipe is 

 produced after every hour, and the paddles are taken 

 in whilst they indulge in the usual screaming convul- 

 sive whooping-cough. They halt for their own purposes 

 but not for ours ; all powers of persuasion fail when 

 they are requested to put into a likely place for col- 

 lecting shells or stones.* For some superstitious reason 



* The following Paper by S. P. Woodward, F.G.S., communicated by 

 Prof. Owen, appeared in the Proceedings of the Zoological So- 

 ciety of London, June 28, 1859. 



The four shells which form the subject of the present note were collected 

 by Captain Speke in the great freshwater lake Tanganyika in Central 

 Africa. 



The large bivalve belongs to the genus Iridina, Lamarck, — a group of 

 river mussels, of which there are nine reputed species, all belonging to the 

 African continent. This little group has been divided into several sub-genera. 

 That to which the new shell belongs is distinguished by its broad and deeply - 

 wrinkled hinge-line, and is called Pleiodon by Conrad. The posterior slope 

 of this shell is encrusted with tufa, as if there were limestone rocks in the 

 vicinity of its habitat. 



The small bivalve is a normal Unio, with finely sculptured valvei. 



The smaller univalve is concave beneath, and so much resembles a Nerita 

 or Calyptrcea that it would be taken for a sea-shell if its history were not well 

 authenticated. It agrees essentially with Litftoglyphus, — a genus peculiar 



