390 Zoological Society : — 



Some Remarks on Aciuila Desmursii (J. Verreaux). 

 By J. H. Gurney, M.P., F.Z.S.* 



M. Jules Verreaux, who first recognized this Eagle as a distinct 

 species, communicated his description of it to Dr. Hartlaub, by whom 

 the species was made known to ornithologists in his admirable work 

 on the Ornithology of West Africa. 



My present object is to put on record some information as to this 

 interesting bird, with which M. Jules Verreaux has been so good as 

 to supply me, and also to give some indications of the changes of 

 plumage to which this species appears liable, and which I have had 

 the opportunity of examining in several examples which now form 

 part of the collection of the Norwich Museum. 



It may, however, be well to premise a few general remarks with 

 reference to the geographical distribution of this Eagle, and to some 

 of the peculiarities by which it is distinguished. 



Aquila Desmursii has hitherto only been found in Tropical Africa, 

 north of the Equator, — specimens having been obtained at Bissao 

 on the western coast, and also in Nubia and Abyssinia, and on the 

 banks of the White Nile. 



It is a small species, intermediate in size between Aquila pennata 

 and Aquila ncevia. From the former it is readily distinguishable by 

 the greater length of all its measurements ; from the latter (as also 

 from Aquila ncevidides) it may, on the contrary, be distinguished by 

 »its less size and, as Dr. Hartlaub well remarks, " by the more deli- 

 cately shaped bill, and by the greater length of the tail " as com- 

 pared with that of the wings. 



Another well-marked distinction, to which Dr. Hartlaub does not 

 allude, is to be found in the presence in Aquila Desmursii of a well- 

 defined, though small, occipital crest, consisting of from eight to 

 nine pointed feathers, the longest of which are fully an inch and a 

 half in length. 



The colouring of this Eagle, described in Dr. Hartlaub's work, is 

 that which characterizes what I believe to be the adult bird after it 

 has newly moulted and has acquired its fresh plumage. In this dress 

 the general colouring of Aquila Desmursii closely resembles that of 

 the adult of Aquila ncevidides under similar conditions, being of a 

 rufous brown, varying in intensity in different portions of the same 

 feather. 



Other specimens of Aquila Desmursii exhibit a plumage of an ex- 

 tremely dark and almost uniform chocolate- colour. These indivi- 

 duals I believe to be immature birds, in which the feathers have 

 been also newly acquired. In this stage they bear a considerable 

 general resemblance in point of colouring to the immature specimens 

 of Aquila pennata, though I have never met with an immature 

 Aquila pennata quite so dark as some specimens I have seen of 

 Aquila Desmursii. In Aquila Desmursii, as also in Aquila ncevidides, 



* This paper will also be published in the Society's ' Transactions,' accompa- 

 nied by a plate. 



