TIIF MALLOPHAGA AS A POSSIBLE CITE TO MKP PHYLOfiENY. 9 



Seeing that Professor Kellogg has now put into words the concrete question which I had 

 already been disposed to answer in the affirmative myself, nothing can he gained by anv 

 further diffidence on account of the unconventional nature of the suggestions put forward. 1 



of the opinion, after a careful preliminary study of the relationships between the Mallo- 

 and their hosts, that when a more complete study of these parasites has been made thej 

 will afford verj considerable help towards solving the vexed question of bird phylogeny. 



In the first place, 1 would suggest that the adoption of a parasitic habit by mallophagous 

 insects occurred even as far hack as late Mesozoic time. My reason for arriving at this con- 

 clusion I put forward with some hesitation, but I have not been able to suggest a better 

 interpretation of the remarkable facts which follow. In each of the two sub-orders of Mallo- 

 family with a distribution confined to mammals. Each of these families is 

 characterised, among other things, by the fact that the tarsus bears only a single claw, while all 

 the bird Frequenting forms have two claws upon the tarsus. One of these families, the Gyro- 

 is an offshoot from the lowest and most generalised of the bird-frequenting forms: the 

 r, the Trichodeclidae, from the higher and more specialised bird-frequenting forms. But 

 coming to marsupials in Australia, there is found upon them a family of Mallophaga with two 

 upon the tarsus, of which the first-described species, Tfeterodoxus longitarsits, was 

 included by Piaget, its author (1880, p. 50^), in the common bird genus Menopon. Even al the 

 present time Neumann (1912, p. 359) has seer no reason to remove it from the genus Menopon. 

 I n fortunately no Mallophaga from American marsupials are known, hut upwards of twenty 

 • have now been taken upon Australian marsupials 1 most of which are still undescribed), 



all belonging to the family Boopidae of Mjoberg 1 , p 21 1. and all closely related to the 



lowest and most generalised bird-frequenting genus. Men'opon. And with the exception of one 

 or two ea~es which may yet be explained by straggling (Mjoberg, ion', p. 22: Neumann, 1012, 

 ipidoe are confined to marsupials, and they are also the only mallophag <u 

 parasites found upon them. 



We find, then, upon the marsupial fauna which has been isolated in the Austro-Malayan 

 region, what we might he justified in calling typical bird parasites. We also find in Australia. 



mallophagan species belonging to practically all the known bird-frequenting genera. But the 

 marsupial parasites are most closely related t" what is admittedly the most generalised bird 

 infesting genus. It seems more reasonable to me to suppose that the migration upon marsupials 

 was of ancient rather than recent occurrence: and I suggest, with some hesitancy, I admit, that 

 the Mallophaga took to a parasitic mode of life at a time when they hail not, as a group, pro- 

 1 » mill the Menopon condition: and that they parasitised both birds and marsupials 

 In fore the true mammals had differentiated out. This, however, has no very direct hearing 

 1 i the main question at issue beyond an indication, if my supposition be at till acceptable, 

 that we have here a case of parasitism that has accompanied practically the whole phyletic 

 history of birds. 



The actual evidence which I have to offer upon the possible clues to bird phylogeny afforded by 

 the parasites is, at present, slender enough, but one or two instances are extremely suggestive. The 

 general relations of parasite to host have been briefly indicated above, and illustrated bv one or two 

 examples. It is not my intention to multiply these. They have been selected quite at r.indom, and a 

 hundred others might equally as well have been given, so repetition can serve no purpose. From 

 this general condition, which enables us to recognise parasites of hawks or of any other order 

 of birds at a glance, 1 wish to proceed to one or two special cases. The question of the re- 

 lationship of parasites of, say, hawks to those of shore birds, or passerines, will have to be 

 left until a much more complete study has been made of Mallophaga in general. Tf this rela- 

 tionship can ever he stated, as I believe it may, then we shall have a clue as to the interrela- 

 tion of the hosts themselves. 



Of the parasites of the Struthiones, Degeeriella asymmetrica is found upon the emu; Li- 

 peurus asymmetricus upon two species of rhea; and Lipeurus quadriinaculalus upon the 

 ostrich and also upon a species of rhea. These three snecies are undoubtedly congeneric, and 

 should be included in a genus distinct from either of those mentioned above. The two latter 

 species are distinguished by a peculiar asymmetry of the chitinous border of the clypeus, the 

 precise form of which is best seen from the accompanying text figure, from all other Mallo- 

 phaga. The young of Degeeriella asymmetrica exhibits a precisely similar structure, which in 



