42 
fuscus seu velox, the African rufiventris, the madagascariensis, and 
perhaps the erythrocnemius of G. Gray, are not true species, but that 
they are subspecies of the common European Nisus fringillarius, 
forming a group amongst themselves, and exhibiting by no means 
the decided differences apparent between fringillarius and pileatus, 
or pileatus and tachiro. 
In the same near relation to the chiquera of Western Africa do I 
consider the true chiquera, Vaill. 30, from India; and this opinion I 
found on the following characteristics. 
The West African chiquera has the body above darker cinereous, 
with very distinct narrow black lines, and the stripe beneath the eye, 
and the black stripe over the eye and ear-covers, are more distinct ; 
the rufous head with darker fine stripes. 
The Indian chiquera has the head without stripes ; the body above 
lighter grey, with very few traces of black bands ; and the black semi- 
circle round the eye is shorter and not so complete. 
But these slight differences will not justify us in considering the 
West African chiquera as a true species distinct from the Indian true 
chiquera ; it is only a subspecies of the latter true species. As such 
we must make a distinction, and as such it must be accorded a place 
in the system. I think the best way is to give a description of the 
oldest known subspecies, and arrange all the other subspecies with 
different names, distinguished by the letters of the alphabet, a, 4, c, 
&c., amongst the true species. In this way it would only be neces- 
sary to give a very short description of the subspecies, consisting of 
the few marks by which it differs from the old known subspecies. 
Until we have discovered all the species contained in one and the 
same subgenus, we can never say with certainty whether a given speci- 
men represents a true species, or only a subspecies; I must there- 
fore confess that in the following descriptions of the family Musci- 
capide, it is very probable that I have described as species some spe- 
cimens which hereafter will be arranged as subspecies, when the whole 
species composing the subgenus are completely known. 
One of the most interesting birds in the collection of Lord Derby 
is a little Falcon, belonging to the subfamily Falconine, which en- 
abled me to correct the characters of the genus Harpagus. 
The characters must be changed as follows :—Bill large, with two 
teeth, slender and indistinct, or strong and distinct ; wings short, and 
in the proportions of the quills very like Nisus seu Accipiter ; toes 
short, and the inner and outer toes of the same length. 
The genus Harpagus must be divided into two subgenera. 
The older subgenus Harpagus must be distinguished by the follow- 
ing characters :—Two strong and distinct teeth; the nostrils placed 
near the end of a soft membrane covering a large cavity; tibia with 
scales not divided. 
Two species, diodon and bidentatus. 
The other subgenus, in which this new species must be placed, 
must be characterized :—Two slender indistinct teeth; the nostrils 
round, very small, and bored in the nasal bones; the first wing- 
