1902.] MR. OLDFIELD THOMAS ON THE BONGO ANTELOPE. 319 



between tliree species, viz., the Indian Spot-billed, the Wild Duck, 

 .and the Pintail {Dcifila acuta) ; in each case both the parents 

 being hybrids. In one instance the drake was a Spot-billed 

 Mallard, and the duck a Pintail Mallai-d, and in the second 

 instance the sexes were reversed. 



In pointing out in what raanner these crosses partook of their 

 parent forms, Mr. Bonhote drew attention to the fact of the great 

 tendency they showed to become white on the underparts, which 

 he was incHned to beheve was a sign of reversion to an earlier 

 form, having regard to the numei'ous species of water-birds in 

 which light-coloured underparts were a constant feature. 



A water-colour drawing of a male Spot-billed and Mallard 

 hybrid in eclipse plumage was also shown ; and it was pointed out 

 that in the winter plumage this individual closely resembled the 

 Mallard, while in the eclipse plumage it showed greater evidence 

 of the other parent. 



Mr. Bonhote drew the following conclusions from his experi- 

 ments, so far as they had at present been cai-ried : — 



(i) Hybridism between three species of surface- feeding Ducks 



is comparatively easy of attainment ; hybrids between two 



species showing no evidence of sterility. 

 (ii) There is a marked tendency in the produce towards white 



underparts. 

 (iii) So far as can be judged, the Pintail is slightly dominant 



over the Mallard, and the Mallard over the Spot-bill, 

 (iv) The chestnut breast and spotted bill are the most dominant 



features of their respective species, 

 (v) In a hybrid one species may be dominant in the winter 



plumage, and the other parent in the eclipse plumage. 



Mr. Oldfield Thomas exhibited a mounted male, and a female 

 skull of the East African representative of the Bongo Antelope, 

 recently described by him as JBoocercus euryceros isaaci ^ on these 

 specimens, which had been obtained by Mr. F. W. Isaac in the 

 deep forest of the Eldoma Ravine, British E. Africa, and presented 

 by him to the ISTational Museum. 



Mr. Thomas drew special attention to the horns of the female, 

 which, in proportion to the size of the animal, were longer than 

 those of the male. The measurements had been given in the 

 paper describing the subspecies. 



This was no doubt the animal to which reference had been 

 made by Mr. F. J. Jackson in a letter read before the Society in 

 1897 ', when the horns of a female were exhibited at the Meeting 

 and figured in the ' Proceedings,' although at that date the native 

 statement that they belonged to a female was not credited, and 

 they were supposed to be those of a male Bushbuck allied to the 

 Inyala {^Tragelaphus angasi). 



1 Ann. Mag. N. H, (7) x. p. 310 (1902). 



2 P. Z. S. 1897, p. 455. 



