FAITXA OF THE AFRICAN LAKES. 531 



preeeiliiig tables. Many details of U\ssei- iiiiportance will be 

 t'oimd (li^cusseil in tiie vni-ious pnpeis on the tVesh-water fishes 

 of Africa uientioned in the bibliogi-apiiy oi- in the British Museum 

 Catalogue (36). jlttenticn uiust. however, be drawn to the most 

 signidcant features, many of wiiich are now brought into special 

 prominence by means of the tabidar method employed. 



The point that first arrests attention is that Tanganyika con- 

 tains no fewer than 146 different forms of fish, which is in 

 itself a remarkable number to come from within the bounds of a 

 single lake. The fact becomes still more striking by a, comparison 

 with Victoria Nyanza wdiicli contains 86 forms, and Nyasa which 

 contains 63. Thus, Tanganyika, has more than half as many 

 species again as Lake Victoi'ia, and over twice as many as JSTj'asa, 

 and this despite tlie fact that Victoria is a bigger luke than 

 Tanganyika and Nyasa, not much inferior to it in size. 



It must next be observed that of tlie 146 species known from 

 Tanganj'ika., no less than 121 are peculiar to that lake, vvhile in 

 comparison 60 out of 86 are endemic in Victoria Nyanza and 43 

 out of 63 in Nyasa. That is to s:iy, nearly 83 per cent, of the 

 fish of Tanganyika are found in that lake alone, while of the 

 species found in Victoria Nyanza, 69 per cent, are peculiar to 

 the lake and in Nyasa 67 percent. Tanganyika, indeed, contains 

 more than double a.s many endemic sjjecies as Lake Victoria, 

 which shows the next largest tota.l . 



Although the number of endemic species in Tanganyika is 

 clearly remarkable, the number of endemic genera is still more 

 so. Of the 55 genera known to occur there, nearly half (26) are 

 found in that lake alone. A comparison with the two other 

 lakes, as instituted above, serves to emphasise the exceptioiial 

 nature of this fact. Two genera onlj' out of 25 are endemic in 

 Victoria Nyanza and five out of 25 in Nyasa. The number of 

 genera recorded from Tanganyika forms a remarkably large 

 proportion of the total enumerated in the table of distribution. 

 A comparison of the figures shows that whereas this la ke contains 

 146 species out of a. grand total of 308, i. e. 47 per cent., it con- 

 tains 55 genera out of 72 — no less than 76 per cent. 



It will now be well to review the list of fishes in rather more 

 detail, dealing in general terms with the various fauiilies and the 

 distribution of theii- representatives in the lakes. T'here is little 

 to comment on as far as the Polypteriche and Lepidosirenidaj a,re 

 concerned. Species of Polypteriis and Protopterus are fairly well 

 represented in the big lakes, but the details of their distribution 

 have no particular significance. — Of the Mormyridte no species 

 have as yet been obtained from the smaller lakes, and the family 

 has but few forms in the three bigger ones Only Victoria 

 Nyanza contains endemic species. — It is interesting to note that 

 the Clupeidfe are to be found in Tanganyika alone, where there is 

 an endemic species of the fresh-water genus Pellojiiola, a.s well as 

 a representative of a closely allied endemic genus. — A few forms 

 of Characinidfe occur in the bigger lakes, of which Tanganjaka 

 and Victoria each contain two types peculiar to themselves. 



