254 Mr. L. Harrison on 



the female, but the black marks in the feathers of the 

 breast are absent. 



The males begin to get the plumage of the adult when 

 about five or six months old, in such a way that, for instance, 

 birds bred in May are indistinguishable from the old birds 

 in January. In the young males the first change is that 

 the throat becomes black. 



The females also acquire the spots on the underside at the 

 same period. 



Although the males have not exactly an eclipse plumage, 

 they yet go back in colour a good deal after the breeding- 

 season, and, for a while, the bright colours are clouded 

 over — even the white spots are less bright. 



I have a flock of fifteen birds, and have bred them during 

 three or four years,, with the result as described above. 



XI. — Bird-parasites and Bird-phylogeny*. 

 By Launcelot Harrison, B.Sc. 



(Text-figure 5.) 



I HAVE always had the intention of, sooner or later, bring- 

 ing under the notice of ornithologists the trend of my work 

 upon bird-parasitesj and I am very sensible of the privilege 

 which is mine in being asked to address the Club this 

 evening. All field-ornithologists are very well aware of the 

 existence of" the Mallophaga, or Biting Lice, of which by far 

 the greater number are distributed upon birds, although 

 they are also found upon nearly all families of mammals. 

 But few, I think, realise how innumerable are the species of 

 these bird-parasites, and what a field they open up for the 

 study of a fascinating side-light on ornithology. It is to 

 this side-light, this oblique illumination of ornithology, that 

 I wish to direct your attention. 



* An address, opening a discussion on this subject, delivered to the 

 British Ornithologists' Club on January 12, 1916. 



