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Annals of the Transvaal Museum. 
as here defined we may be able to place a number of genera together in 
groups having great similarity as regards habits, nests, eggs, and external 
structure. The case of Prinia may be cited as an example of convergence, 
for in its general appearance and habits it much resembles Cisticola ; but 
it has only ten tail feathers (as against twelve in Cisticola), and its nest 
and eggs are markedly different. Another instance is to be found in 
Sphenoeacus which, while closely resembling Cisticola in appearance and 
habits, and in having twelve tail feathers (not ten as noted by some writers), 
shows us, however, by its nest and eggs, and by some points in its structure, 
it belongs to a group comprising amongst other genera, Bradypterus , 
Calamocichla, and Acrocephalus . Melocichla so closely resembles Cisticola 
erythrops that when M. mentalis was first described, it was placed in the 
genus Cisticola ; Melocichla pyrrhops, on the other hand, is now placed 
in the synonymy of Cisticola erythrops ; and yet from what I know of the 
habits of. Melocichla, I feel sure that its nest and eggs (which have not 
so far been described) will prove to be most like those of Sphenoeacus . 
Examples of the principle of divergence may be found in the genera Apalis 
and Camaroptera, which while quite different in colour from Cisticola q 
yet show by their structural characters, nests, and eggs that they are 
closely related to that genus. 
Throughout the genus Cisticola , as at present understood (excluding 
Hemipteryx, which has been placed in the synony my of this genus by some 
authorities), the species show a great similarity to one another in regard 
to general appearance, habits, nests, and eggs, and there seems to be no 
doubt that they have all originated from a common stock different from 
Prinia and Sphenoeacus. There are almost as many minor differences in 
structure as there are species in the genus. We find a number of species 
all enjoying much the same conditions of environment, and they all retain 
the same plain-coloured plumage ; where, however, slight differences in 
the conditions have affected the individual species, slight modifications of 
structure in consequence of these conditions have become necessary to 
the existence of the species. On the other hand, where a species has 
adopted a new set of conditions, such as inhabiting dense forests in place 
of less sheltered situations, where a plain-coloured plumage would not be 
so necessary to the existence of the species, and there would be scope for 
the development of new colours, there we may expect to find distinct new 
characters clearly marking it off from its supposed former congeners ; 
and with the aid of this hypothesis we may be able to account for such 
genera as Apalis and Camaroptera. 
It is evident from what has just been said that all the species of 
Cisticola still retain a number of characters in common, and they are 
easily recognized as belonging to one genus. Under the circumstances 
it seems best to leave the genus as it stands, and note in doing so that 
minor differences of structure should be as much considered as those of 
colour in the definition of species. 
Having come to this conclusion in regard to the Cisticolidae, I have 
thought it advisable when dealing with the South African species to treat 
them under a number of groups, so that the individual variations may 
be more clearly shown. In this connection, an innovation has been 
