2 MR. G. A. BOULENGER ON A COLLECTION 
made under more favourable circumstances, would considerably modify our views on 
the general character of this most important section of the fauna. 
How incomplete the collection is may be partly realized from the fact that, of the 
six species previously described from Tanganyika, only one was rediscovered by 
Mr. Moore. His series of sketches executed from fresh specimens, free use of 
which he has kindly given me, thus enabling me to represent some of the new 
species in their natural colours, also indicate the existence of several fishes which are 
unrepresented in the collection. Large fishes, owing to the impossibility of preserving 
them, had to be left behind, and the difficulties of transport by carriers resulted in the 
loss of several jars containing spirit-specimens. Nevertheless, small as it is, and 
though deficient in any but typically African freshwater forms, the collection is of great 
interest, and Mr. Moore well deserves the thanks of all zoologists for the manner in 
which, amid so many difficulties, he has succeeded in affording us a first glimpse at a 
fish-fauna which has so long remained a mystery. 
A study of the freshwater fishes of Africa has hitherto led to the assumption that 
the bulk of the fauna originated in the region of the great lakes, whence they have 
radiated towards the Mediterranean and the Atlantic and Indian Oceans—a view based 
on the close affinity, often amounting to specific identity, of the fishes of the Nile, the 
Niger, the Congo, and the Zambesi. The homogeneity of the fauna is absolutely 
opposed to the conception of the great watersheds having been stocked from the sea, 
within the geological period of which these fishes are representative, this being evident 
even in the case of such forms as ates and Tilapia, which are known to enter salt water. 
Nothing contrary to this theory is brought to light by an examination of the fishes 
obtained by Mr. Moore in Lake Tanganyika. The striking character of the Tanganyika 
fish-fauna, as revealed by Mr. Moore’s collection, is the extraordinary variety of the 
Cichlide 1. This is a natural group distributed all over Africa, including Madagascar, 
but, although rich in species, nowhere else showing within a limited area anything like 
the modifications of structure described in this report, which have necessitated the 
establishment of nearly as many new genera as were previously known from the whole 
of Africa. The generalized characters of some of the Cichlide occurring in Lake 
Tanganyika, regarding as indicative of generalization the greater development of the 
anal fin, consistently with the system followed in classifying their more primitive 
allies the Centrarchide?, and the extent of the lateral lines, both of which are 
complete in some of the newly-discovered forms*, afford further support to the 
1 See P. Z. 8. 1898, p. 132. * Cat. Fish. 2nd ed. i. p. 2 (1895). 
* The lateral line has usually been described as “ interrupted” in the Cichlide and other groups in which 
it has a similar disposition. ‘This expression conveys a serious misconception, and I have replaced it in the 
diagnoses ot the Cichlide and the Serranidw allied to Plesiops by “ lateral lines two,” the necessity for this 
change being particularly obvious in the case of some of the species described in this report. Fishes had no 
doubt originally a greater number of lines of sense-organs along the body, as we may still observe in many of 
