262 
AFRICAN BRISTLE-BILL. 
It exhibits, in short, some of the typical characters 
of each, and yet it is so equally connected to both, 
that, for the present, we cannot determine to which 
group it strictly belongs. To Dasycepliala it is re- 
lated by its lengthened, straight, and abruptly hooked 
bill ; bj r a few incurved setaceous feathers and hairs 
over the nostrils ; by the length of the tarsus and 
of the middle toe ; and, by the great inequality be- 
tween the lateral toes. On the other hand, its 
affinity to Triehophorus is shewn in its compressed 
bill, the structure of its wings, and its geographic 
station. It is usual to term a species possessing 
such a union of characters as those just described, — 
a sub-genus, seeing that it does not precisely agree 
with the definitions of any group hitherto named. 
But this mode of proceeding may be carried too far ; 
a little consideration will convince those who adopt 
it, that in every natural group there must be oscu- 
lent or aberrant species, without winch every genus 
would be isolated. If there is no approach in struc- 
ture from the species of one group to the species of 
another, there would not be that almost impercep- 
tible gradation in nature which every one sees and 
acknowledges. Some limits, therefore, must be put 
to the creation of sub -genera, and every efl’ort should 
be made, in the first instance, to ascertain the 
station of such forms among their congeners, and 
this can only be done by extensive analysis. In the 
present instance Dasycephala, according to the views 
we have elsewhere published, is itself a sub-genus, 
and such also is Triehophorus ; it consequently 
