4.28 REPORT—1905. 
from these data that Lake Victoria has long been isolated, whilst Lake Rudolf 
has until very recently been in communication with the Nile. 
Lake Tsana, which is now the source of the Blue Nile, has recently yielded a. 
large collection of fishes, showing a great variety of Cyprinids, either endemic 
or identical with species occurring in the eastern watershed, and closely allied 
to those of Palestine, but with no special Nile affinities. The discovery of a 
Loach (Nemachilus), the first known from Africa, points to an immigration from 
the Jordan, probably through the old Erythrean Valley. The only species which 
Lake Tsana has in common with the Nile (Tilapia nilotica) occurs also in the 
Hawash and in the Jordan. 
From the vastly increased information we now possess of the fishes of the Nile- 
system, we are justified in believing in great changes in the hydrography of this part, 
of Africa. The fishes of Lake Tsana would support Professor Gregory’s conclusion 
as to a communication with the Jordan through a river running along what is now 
the Red Sea, whilst those of the Lower Nile point to a direct communication 
between the latter and the Jordan, as advocated by Professor Hull, migrations: 
along two distinct channels having taken place at a time when the Mediterranean, 
did not extend so far to the east as it does at present, and the Indian Ocean 
had not penetrated into the Erythrean Valley. A better knowledge of the fishes: 
of Egypt has disposed of Professor Gregory’s arguments against a former communi-. 
cation between the Lower Nile and the Jordan. Quoting Dr. Giinther, Professor: 
Gregory, in his book ‘The Great Rift Valley,’ published in 1896, has laid stress; 
on the supposed facts that Hemichromis, a genus of Cichlida, is not represented in 
the north-eastern part of Africa, but chiefly on the West Coast and in the 
central lakes, and that the Clartas of the Jordan is not the species of the Lower 
Nile (C. anguillaris), but that of the Upper Nile (C. macracanthus), adding that it 
is of no use, therefore, to assume the existence of a connection between the Lower 
Nile and the Jordan in order to account for the existence in the latter of fishes 
which do not occur in the former, These examples were ill chosen, for as regards 
the Hemichromis (including Paratilapia) the statement has been disproved by 
the discovery, in 1881 and in 1903, of two species in Lake Mareotis; and as to. 
the Clarias I have been able to convince myself that the species named C. macra- 
canthus by Giinther is identical with C. lazera, a fish common throughout the: 
Nile and over a considerable part of Africa. 
The Nile in its widest sense, but without the great lakes, has 101 species, not 
including those that enter the sea: twenty-seven do not extend north of Char- 
toum, whilst only six are restricted to the river below the First Cataract. The 
most important additions made since Dr. Giinther’s account of them in ‘Petherick’s 
Travels’ are several Mormyrs, Barbus, and Synodontis, three Cichlids, a Xeno-. 
mystus, a Nannethiops, a Discognathus, a Barilius, a Chiloglanis, a Fundulus, 
an Eleotris, and the remarkable genera Physailia, Andersonia, and Cromeria, the 
latter the type of a new family. 
Thanks to the collections made by Sir Harry Johnston and Col. Delmé 
Radcliffe, with the help of Mr. Doggett, and by M. Alluaud, supplementing those of* 
Dr. Fischer, we may now draw up a list of twenty-five species from Lake Victoria. 
The comparative scarcity of animal and vegetable life in this great lake perhaps 
precludes expectation of a great increase in the number of species in the course 
of further exploration. Most of the species are endemic and among the most 
remarkable types may be mentioned a Discognathus, a Mastacembelus (probably 
the fish noticed by Grant as a Stickleback), and a peculiar genus of Cichlids, 
Astatoreochromis. No Polypterus has yet been found. 
Lakes Albert and Albert Edward, recently visited by Mr. Moore, have fur- 
nished examples of nine species, mostly Nilotic in character, the most interesting 
being a Petrochromis, on account of its close affinity to a Tanganyika species. 
Lake Rudolf, as stated above, differs hardly from the Upper Nile, only three 
of its sixteen species being indicative of immigration from the Kast. Not a single 
form is endemic. 
The Senegal must have been very thoroughly explored by Dr. Steindachner 
thirty-five years ago, as a large collection made a few years since by the late 
