81 [Vol. xix. 



was a mutation or sport resembling a character which had 

 become fixed in a nearly allied species^ and that similar 

 instances had occasionally been found among other groups 

 of birds. 



In dealing with domestic varieties^ Mendelism had shown 

 that such sports might easily become fixed^ and the occurrence 

 of this sport in the Eiders tended to form a link in the 

 evidence that evolution had in some cases proceeded from 

 mutations, 



Mr. Bonhote also pointed out that a dark V-shaped mark 

 might sometimes be traced during the progress of the moult 

 from the eclipse to the full plumage, owing to the dark 

 feathers under the chin and along the line of the lower 

 mandible being the last to be moulted. This dark mark 

 could not, however, be confused with the true V-shaped "mark, 

 as this latter lay within the line of the lower mandibles and 

 7iever reached the apex of the chin. There was a further 

 difference between these markings, for in the true V the 

 arms narrowed as they diverged, whereas in the transient V^ 

 seen during; the moult, they became broader as they diverged. 



Mr. Bonhote suggested that -S. mollissima ought to be 

 regarded as the older form, since in this species the V-shaped 

 mark and the backward extensions of the beak-sheath were 

 less developed than in S. v-nigrum. 



In S. dresseri the backward extensions of the beak -sheath 

 had become broader and the V was generally ill-defined, 

 while in S. spectabilis both these characters had attained their 

 maximum development. Following another line of evolution, 

 he remarked that in S. v-nrgrum the bill resembled that of the 

 Common Eider, but the V was fully developed. In S. stelleri 

 the backward extensions of the bill were extremely reduced, 

 and the whole of the chin was suffused with black. 



Dr. Ernst Hartert described the following new species 

 and subspecies of African birds : — 



Xenocopsychus, gen. n. 

 Closely allied to Copsychus, but the bill is slightly more 

 depressed, the culmen less arched, the operculum covering 



