FAUNA OF THE AFRICAN LAKES. 



545 



Name of Species. ^^^P"' 'Q'^''''^ 



^ yika. Nyanza. 



Family Limnjjid^. 



Limuaja iiatalensis P P 



„ nyanssB ... E 



„ undussumai ... P 



Isidora coulboisi E 



„ forskali ... P 



„ nyassana 



„ vaiidabeli E 



„ strigosa ... P 



„ succineoides 



„ trans versalis ... E 



„ trigona E 



Physopsis africana 



„ ovoidea ... P 



„ tanganyicaj E 



Family Planorbidje. 



Plaiiorbis adowensis P 



„ alexandrina P 



„ apertus 



„ bridouxiana E 



„ clioanomplialus ... ... P 



„ cvavvfovdi P 



„ gibbonsi ... P 



„ lamyi E 



„ lavigeriaims E 



„ monceti E 



„ stanleyi 



„ sudanicus P P 



„ victori;e ... E 



Family Ancylidjs. 



Alley lus stulilmanni ... E 



„ tanganyiceiisis E 



8 families 1E,7P. 7 P. 



35 genera 24E,llP. 11 P. 



(35) 



Albert Edward t^. Other parts of 

 ^y^^'^- Nyanza. Nyanza. the world. 



6P 



P P 



Natal. 

 E. Africa. 



Egypt, Natal, 



[Angola, 



E. Africa. 



E. Africa, Natal. 

 E. Africa. 



... Abyssinia. 

 ,.. Egypt. 



Cape Colony, 

 E. Africa. 



R. Nile. 



6P. 2P. 



6 P. 6 P. 2 P. 



133 species 76E,8P. 11E,17P. 10E,14P. 4E,9P. 1E,9P. 2 P. 



(84) (28) (24) (13) (10) 



A list such as this, with 133 species, requires a somewhat 

 detailed analysis to bring out the points of most interest and 

 importance, although, indeed, the tabular form reveals the excep- 

 tional nature of the Gasteropod fauna of Tanganyika. In the 

 tirst place it will be noticed that no less than 84 species are 

 recorded from Tanganyika, which is clearly an exceptional number. 

 That this is so, is shown by a comparison with the known fauna 

 of the two lakes which come nearest in size, for Victoria Nyanza 

 can muster but 28 forms and Nyasa only 24. Thus Tanganyika 

 contains three times as many Gasteropods as Lake Victoria and 

 more than three times as many as Nyasa. 



Secondly, be it observed, that of the 84 Tanganyika species, no 

 fewer than 76 are endemic, while correspondingly only 11 out of 

 28 are peculiar to Victoria Nyanza and 10 out of 24 to Nyasa, 



