No. 569] ECTOPARASITES OF MAMMALS 263 



this host group strongly suggests that the one-clawed eon- 

 dition common to all other mammal-infesting Mallophaga 

 is a derivative from the original two-clawed condition 

 characteristic of the parasites of birds and of these ancient 

 mammals. The two-clawed condition is, of course, the one 

 common to insects generally and is characteristic of the 

 Atropids, in whom I am inclined to see the ancestors, or 

 near-ancestors, of the Mallophaga. All of the Anoplura. 

 it may be added, which are exclusively mammal-infesting, 

 are one-clawed. 



In this connection the suggestiveness of the fact that 

 in face of the examination of many specimens of half a 

 dozen species of kangaroos and wallabies, no Anoplura 

 have yet been found on the Marsupials, may be referred 

 to. I am coming strongly to believe that there is no such 

 wide ordinal separation of the Mallophaga and Anoplura 

 as our clinging to the fetich of "biting and sucking 

 mouth-parts" as basis for radical classincatory separation 

 has led us to effect. I believe, with Mjoberg, that the tw. . 

 groups of parasites have a fairly near genealogical 

 affinity, their differences, which are particularly those of 

 mouth-parts, being adaptive rather than palingenetic hi 

 character. The Anoplura have gone on from the Psocid- 

 Mallnphagan condition to a more specialized parasitic 

 habit, and are the extremes of a general line of ecto- 

 parasitic evolution. The absence of sucking lice from the 

 kangaroos may mean that the Marsupials are older than 

 the Anoplura! No other considerable group of mam- 

 mals, except certain families of strong-smelling Carni- 

 vora, is free from the blood-sucking parasites. 



There are but two Edentates in the host list, one, the 

 Cape Ant bear, Orycteropus afer (family Orycteropo- 

 didsp) of south and central Africa, harboring a sucking 

 louse, of genus and species peculiar to it, and the other, 

 the three-toed sloth, Bradypus tridactylus (family Brady- 

 podidae) of eastern South America, harboring a Mallo- 

 phagan of species peculiar to it but of the genus (ii/rnpus 

 which is the less scattered, although still rather catholic, 



