INTRODUCTION. 
101 
the turraccos ; the violet species ( Mmophaga vio- 
lacea ) has ever been a favourite bird with orni- 
thologists, and it is more frequently met with in the 
forests of Senegal than on the Guinea Coast, where 
M. Isert, its first describer, mentions it as parti- 
cularly rare ; besides the two species of this group 
which we actually know to be natives of this coast, 
there are two others which authors describe as 
likewise natives of Senegal. 
The existence of at least three species of halcyon, 
where not one is found, as we believe, in Southern 
Africa, proves that the distribution of these forest 
king-fishers, or rather crab-eaters, are distributed 
in a lateral direction within a certain distance on 
each side of the equator. The only exceptions 
being two or three species found in Australia., 
Of the gallinaceous or rasorial birds little can 
be said. Western Africa appears the metropolis of 
the Guinea fowls, and our list contains a species 
apparently new. There are, no doubt, on the 
sandy districts, several other species of land-grouse 
( Pterocles ) and of partridges, than those few which 
have yet come to our hands. 
The mouth of the river Gambia is frequented by 
several aquatic birds, which will be more particularly 
noticed in another volume. 
Having now, by this rapid sketch, sufficiently 
prepared the reader for entering into the details of 
this volume, we shall at once proceed to describe 
the subjects themselves. 
It will hardly be necessary to inform the orni- 
