420 



NA TURE 



[August 24, 1905 



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 furnished examples of nine species, mostly 

 Nilotic in character, the most interesting being a Petro- 

 chromis, 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 East. Not a single form is 

 endemic. 



The Senegal must have been very thoroughly explored 

 by Dr. Steindachner thirty-five years ago, as a large collec- 

 tion made a few years since by the late M. Delhez has not 

 resulted in a single addition to the list of species. The 

 Gambia, on the other hand, is now much better known 

 than it was, thanks to the two visits of the late Mr. 

 Budgett, to whom we owe the discovery of two species. 

 But it is the Niger which, through the collections made by 

 Dr. C. Christy, the late Captain G. F. Abadie, Mr. 

 Budgett, and especially Dr. Ansorge, has been productive 

 of the most important additions to our knowledge. The 

 most striking discoveries are the type of a new family, 

 Phractolcemus, since re-discovered in the Ubanghi, and 

 Polycentropsis, the first representative of the Nandidaj in 

 Africa. Leaving aside species entering the sea, we now 

 know fifty-four species from the Senegal, forty-one from the 

 Gambia, and ninety-six from the Niger, the lower course 

 of the latter being the most productive. A remarkable 

 feature of these rivers is the comparative paucity of 

 Cyprinids, and the total absence in the first two of the 

 genus Barbus, which also appears to be absent from the 

 Chad basin. 



Our knowledge of the piscine inhabitants of the rivers 

 flowing into the Atlantic between the mouths of the Gambia 

 and of the Niger has also made considerable progress. The 

 fishes of Liberia, collected by Dr. Biittikofer, have been 

 described by Dr. Steindachner, and those of the Gold 

 Coast, collected by the late Mr. R. B. Walker, have been 

 reported upon by Dr. Gunther. Sixty-seven species are on 

 record from this district, twenty-four of them being 

 endemic. 



Further South, North Cameroon has yielded several 

 additions, for a knowledge of which we are indebted to Dr. 

 Lonnberg, whilst South Cameroon, together with the 

 Gaboon district, has been diligently explored by Mr. G. L. 

 Bates, with the result that a great number of new species 

 have been brought to light. This part of Africa is 

 specially interesting from the fact that its rivers interlock 

 with the head waters of the Sanga, which belongs to the 

 Congo basin, and, the fishes being mostly the same in 

 both watersheds, in that district, a sort of passage is 

 established between the Gaboon and Congo faunas. Among 

 the most remarkable forms discovered by Mr. Bates we 

 may mention the genera Microsynodontis, Allabenchelys, 

 and Procatopus. Since Dr. Sauvage reported, twenty-five 

 years ago, on the fishes of the Ogow^, a small collection 

 has been made by the late Miss Kingsley, and described 

 by Dr. Gunther, and a number of new species have been 

 characterised by Dr. Pellegrin. The number of species 

 now known from this part of Africa amounts to eighty- 

 seven for South Cameroon and the Gaboon, and fiftv-four 

 for the Ogow(5. Very curiously, among them we miss 

 Polypterus and Calamichthys, which occur in the Lower 

 Niger and Old Calabar, and again in the Chiloango — a 

 remarkable instance of discontinuous distribution, which 

 cannot be accounted for by physical conditions, so far as 

 we are acquainted with them. 



The Congo system (exclusive of Lake Tanganyika), from 

 which only about ninety species of fishes were known ten 

 years ago, proves to be far richer than any other, for, 

 incompletely explored as it still is. it has already furnished 

 examples of 265 species, forty-five of which have been 

 added since the publication of the work " Les Poissons du 

 Bassin du Congo " in iqot. In fact, every collection 

 made even in its most accessible parts adds new species 

 to the list, and many of its rivers have never yet been 

 fished for scientific purposes. No doubt we do not know 

 more than two-thirds of the fishes of the Congo. The 

 riches in Mormyrids, Characinids, Silurids, Cichlids, 



NO 1869, VOL. 72] 



Mastacembelids, is something surprising, not only in the 

 number of species, but also in their extraordinary variety 

 of structure ; and as many as seven species of Polypterids, 

 out of the eleven that are now known, occur in this river- 

 system. With the exception of the Cromeriidae and 

 NandidK, all the families known from the sub-region have 

 representatives in the Congo. 



Lake Tanganyika, now forming part of the same hydro- 

 graphic system, has a somewhat different fauna, consist- 

 ing mainly of Cichlids, to which we have specially alluded 

 in an earlier part of this .Address. But there are, in addi- 

 tion, a number of Silurids and Cyprinids, a few Masta- 

 cembelids and Characinids, a Cyprinodont, and a Poly- 

 pterus. The latter belongs to a species otherwise restricted 

 to the Congo, and of the four Characinids two are Congo 

 and two are Nile forms. The total number of Tanganyikan 

 species of fishes amounts to eighty-five, but, no doubt, many 

 more await discovery. As I pointed out in reporting on 

 Mr. Moore's second collection, I have reason to think that 

 we do not know more than half the species of fishes 

 inhabiting this extraordinary lake. The collection which 

 has just been brought home by Mr. Cunnington will greatly 

 add to our knowledge. I may here mention that Mor- 

 myrids, which were believed to be absent from Tangan- 

 yika, are therein represented by two species. 



Lake Rukwa has recently been explored by Dr. Fiille- 

 born, but the fishes, which have been referred to eleven 

 species, belonging to widely distributed genera, have not 

 been studied with a sufficient comparison-material : they 

 appear to be mostly endemic forms. 



Lake Mwero has representatives of fourteen species, 

 five of which are endemic, the remainder being found also 

 in the Congo or in the Zambesi, or in both. 



The Zambesi, so far as we know it — and its upper parts 

 have scarcely been explored — appears rather poor in fishes, 

 only forty-one species having been recorded. All the 

 genera are also represented in the Congo and in the Nile. 

 Seven of the Zambesi species occur also in Lake Nyassa 

 and the L^pper Shir^, whilst in the present state of our 

 knowledge twenty-seven species, mostly Cichlids, may be 

 regarded as endemic to the lake and the Upper 

 .Shire. It is perfectly clear, however, that Lake Nyassa 

 differs far less from the Zambesi than Tanganyika 

 does from the Nile or Congo ; and, although the 

 Cichlids are likewise represented by some remarkable 

 genera, they cannot compare for variety with the other 

 great lake the fauna of which has been such a surprise. 

 Both the Zambesi and Lake Nyassa lack representatives 

 of the Polypteridae. 



About forty-five years ago a collection of fishes was 

 made in Lake Ngami, and twelve species were described 

 in a very unsatisfactory manner by the late Count F. 

 de Castelnau ; unfortunately the types of these species are 

 lost, and it is difficult to form an idea of their affinities. 

 We know, however, that the lake, which is now rapidly 

 drying up, was then inhabited by a Mormyr, a Clarias, 

 a Characinid, and several Cichlids. 



The rivers of Angola have been but imperfectly explored. 

 They have yielded a number of Cyprinids and Cichlids, 

 a few Silurids, Mormyrids, and Cyprinodontids, and the 

 type of the remarkable genus Kneria, the second species 

 of which inhabits East Africa. 



III. The Eastern Slb-region. 



.\s was rr.entiohed in the beginning of this Address, 

 latitude goes for little in the distribution of fish-life. This 

 is proved by the very marked difference in general 

 character of the fish-faunas of Abyssinia and Africa east 

 of the great Rift \'alley as compared to the Nile and 

 Central and West Africa. No Polypterids or Masta- 

 cembelids, few Mormyrids, Characinids, and Cichlids, but 

 a great number of Cyprinids, mostly Barbus, characterise 

 this sub-region. Omitting catadromous forms, the list 

 of fishes consists of one Lepidosirenid, six Mormyrids, 

 eight Characinids, seventy Cyprinids, twenty Silurids, one 

 Kneriid, six Cyprinodontids, and seven Cichlids. 



Lake Tsana, with the upper affluents of the Blue Nile, 

 differs very strikingly in its fishes from the Nile, with 

 which it has only two species in common, a Silurid 

 (Bagrtis docmac), and a widely distributed Cichlid (Tilapia 

 nUotica), which occurs also in the Hawash and in 



