158 Mr. J. H. Gurney on 



It has given me much pleasure to seud for illustration 

 a skin I made of the handsomest male specimen of these 

 Swifts taken on the above occasion. The coloured figure of 

 this Swift illustrating Dr. Heermann's Report (1853, plate 

 xviii.)j already alluded to, is an unusually poor representation 

 and, to me, hardly recognizable. In fact I do not believe 

 there is a good coloured figure of this truly interesting bird 

 in existence, and I have availed myself of the present oppor- 

 tunity to present a coloured figure of a fine old male bird. 



28th September, 188(3. 



XV. — On Falco babyloiiicus and Falco barbarus. 

 By JoHiM Henky Gurney. 



In ' The Ibis ' for 1882, p. 439, I wrote respecting Falco 

 babylonicus that it seemed chiefly to differ from F. barbarus 

 by its larger dimensions, and I added that, at that time, I 

 believed I had never seen an adult male of F. babylonicus. 

 Since then the British Museum has acquired — partly through 

 the liberality of Mr. Hume, and partly through that of other 

 donors — a very fine series of Falco babylonicus, which I have 

 recently had an opportunity of examining, arriving, as the 

 result, at the conclusion that, whilst the females of F. baby- 

 lonicus are decidedly larger than those of F. barbarus, the 

 males of F. babylonicus differ but little, either in size or 

 colour, from F. barbarus, in which latter species the propor- 

 tionate distinction of size between the sexes is less than in 

 F. babylonicus. I observe, however, that the adult males of 

 F. babylonicus, when compared with the few African adults 

 which I have examined of F. barbarus, exhibit, in most 

 instances, a somewhat paler grey on the lower part of the 

 back, upper tail-coverts, and basal portion of the tail ; that 

 most of them have a larger extent, and sometimes a brighter 

 tint, of rufous on the nape and sides of the neck, and also 

 more decidedly rufous foreheads. 



Generally s^jeakiiig, the adult females of F. babylonicus 

 exhibit a slightly darker tint of grey on the upper surface 



