8 THE MALLOPHAGA AS A POSSIBLE CI.UE TO BIRD PHYLOGENY. 



"I can see but one answer. That is, that the parasite species has been handed down 

 practically unchanged to the present specifically and even generically distinct several bird 

 species from their common ancestor of earlier days. The parasite species dates from the days 

 of this ancestor." 



It will be noted that Kellogg refers only to the same parasitic species being found on 

 allied bird forms in Europe and America, but the argument holds also for allied forms of 

 parasites. Having come to the conclusion that we had, in the Mallophaga, to deal with a 

 case of retarded evolution, the next question that naturally arose was — How far back does this 

 retardation extend? In other words, would it be possible by a careful study of the Mallophaga, 

 and of their host distribution, to gain any clue as to the inter-relationship of the hosts them- 

 selves. As the result of a little preliminary inquiry, I became convinced that there was some 

 hope of such a result, and in September, 191 1, read before the Sydney University Science 

 Society, a short paper discussing this possibility, a summary of which was printed in the 

 Annual Report of the Society for that year. 



The propriety of attempting to indicate phyletic relationships by such means as a study of 

 the distribution of parasites may be questioned. But in the case of birds, in attempts to 

 satisfactorily classify which all the resources of morphology and embryology have been em- 

 ployed in vain, I would submit that nothing that is likely to throw a gleam of light should 

 be lightly set aside. Birds are easily divided into a number of admittedly natural groups, but 

 hardly any two systematists can be found in aereement as to the relationship of these groups 

 among themselves. Professor Newton was so dissatisfied with all attempts at classification that 

 he published his wealth of ornithological learning in the form of a "Dictionary of Birds," just 

 to avoid a systematic arrangement. Embryology, which has helped to clear up so many phyletic 

 difficulties, has only produced a series of results monotonous in their uniformity. Morphology, 

 too, has merely confirmed the general sameness of bird structure, the efforts of Garrod, Forbes 

 and others to establish a classification on the variation of this organ, or the presence or absence 

 of that, all ending in failure. One has only to compare any of the recent attempts at classi- 

 fication of birds, to see how hopelessly at variance are their authors. Bevond a general agree- 

 ment that the passerine birds constitute the highest and most specialised order, nothing is 

 certain. 



In view of the fact that all the ordinary biological means have failed, I think it quite 

 justifiable that an attempt should be made to see what light may be thrown upon bird phylogeny 

 by a study of bird parasites. 



An examination of the literature to see whether the above idea had occurred to any other 

 worker disclosed only one suggestive sentence, prior to a paper by Kellogg in 1913. Giebel 

 and Taschenberg, two monographers of the Mallopliaga, give no sign of having recognised 

 any remarkable condition of affairs in the relation of parasite to host. Piaget, although he 

 clearly exposed this condition, did so more or less accidentally, and has not indulged in any 

 speculations on it. Kellogg, on the other hand, wrote (Kellogg & Kuwana, 1902, p. 458): — 



"It was hoped that the character of the parasites found on the strictly Galapagos Island 

 bird hosts might throw some light on the relationships of these birds to continental genera and 

 species " 



This hope was defeated by the extraordinary conditions obtaining on the islands, birds of 

 different orders huddling together promiscuously on the bare rocks, and their parasites becom- 

 ing hopelessly mixed. The germ, however, was with Kellogg in 1902, and in 1913 (p. 138) he 

 writes much more definitely : — 



"Of the other Mallophagan genera found on the tinamous two that specially characterize 

 the pheasants and other gallinaceous birds are. by odds, the most commonly represented. And 

 this condition suggests another interesting problem. Is it going to be possible to get suggestions 

 regarding the phyletic affinities of hosts from the character of their parasitic fauna? Take, 

 for example, an order of birds troublesome to the ornithological taxonomists. Will the evidence 

 of the presence on members of this order of certain parasitic genera characteristic of another 

 order, indicate their affinities to this second order? It does indeed seem, in the case of the 

 Tinamiformes and Galliformes, as if the evidence from the Mallophagan distribution was in con- 

 formity with that suggested by certain structural similarities in the two groups." 



