BIRD-PARASITES AND BIRD-PHYLOGENY 51 



small numbers, while the " common House-Fly " {Musca 

 doDiesticd) is not mentioned as even present ! One of the 

 most interesting features of the phenomenon is the fact that 

 the invasion has occurred for " at least five or six years in 

 succession," varying in intensity, but always reaching its 

 maximum in the upper room. As yet there does not seem 

 to be any satisfactory explanation of these troublesome 

 fl) -raids. They always occur in the autumn, and Dr Sharp, 

 in the Cambridge Natural History (vol. vi.), repeats a sug- 

 gestion that "the individuals are seeking winter quarters." 

 Since, however, we have as yet very little information, if 

 any, as to how and where/ flies in general pass the winter, 

 such an explanation must be taken for what it is worth. 



BIRD-PARASITES AND BIRD-PHYLOGENY. 



At a meeting of the British Ornithologists' Club, held on the 

 1 2th January last, an interesting discussion took place upon 

 the value of a close study of bird-parasites as a means of 

 obtaining a more accurate knowledge of the inter-relations 

 of the various groups {e.g. Orders) into which birds have 

 been classified. The discussion was opened by Mr Launcelot 

 Harrison, B.Sc, Research Scholar, Quick Laboratory, Cam- 

 bridge, and continued by Mr Bruce Cummings, of the Entomo- 

 logical Department, British Museum, Mr T. Iredale, and 

 others. A detailed report is promised for the next number 

 of the Ibis ; but as this publication may not be accessible to 

 the majority of our readers we have decided to reproduce, 

 at least partially, the summary of the discussion which has 

 just appeared in Bulletin No. ccxii. of the Club. 



The resume of Mr Harrison's opening paper includes 

 the following remarks :— " The bird - parasites referred to 

 belong to the insect order Mallophaga, and are minute 

 insects, of an average length of two millimetres, found upon 

 all birds. They are completely parasitic in all stages of their 

 life-history, the eggs being attached to the feathers of the 



