8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Acanthocephala, while the heterotochthonous hosts carry both pecuHar 

 species and species common to both northern hosts and southern hosts. 

 He carries the study further to inchide host-parasite conditions among 

 mammals, birds, reptiles, amphibia, and freshwater fish. In conclusion 

 he says, '* The worms prove a valuable aid in analytical study of 

 zoogeography and paleogeography." 



There could hardly be a clearer example of the use of parasite data 

 in study of these broad problems. It seems natural therefore to use 

 the phrase " the von Ihering method " of utilizing host-parasite data. 



Five years later than von Ihering's earlier paper, but six years 

 earlier than the paper last cited, Vernon Kellogg (1896) discussed 

 the biting lice of birds as giving evidence of genetic relationships 

 between their hosts. In a later paper (1913) he notes the following 

 instances of species of these mallophagan parasites being common to 

 American and European birds not of the same species : The American 

 and the European avocets do not meet, yet they have two mallophagan 

 species in common ; American and European coots similarly do not 

 meet, yet have five mallophagan species in common ; American and 

 European bitterns are infected by the same mallophagan parasite. 

 Other examples are American and Old World water-ousels ; one 

 American and one Old World kinglet ; one mallophagan species 

 common to two Old World and two New World crows. He writes 

 (1896, p. 51): 



The occurrence of a parasitic species common to European and American 

 birds, which is not an infrequent matter, must have another explanation than 

 any yet suggested. This explanation I believe is, for many of the instances, 

 that the parasitic species has persisted unchanged from the common ancestor 

 of the two or more now distinct but closely allied bird-species. 



Kellogg repeatedly emphasized this idea of the interpretative value 

 in bird-taxonomy of evidence from their parasites. In 1902, in a 

 report by himself and Kuwana upon the Mallophaga of Galapagos 

 Islands birds we find the paragraph : 



It was hoped that the character of the parasites found on the strictly Gala- 

 pagos Island bird hosts might throw some light on the relationships of these 

 birds to continental genera and species, but our knowledge of the distribution 

 of the Mallophaga is yet far too meager to give much value to suggestions and 

 especially as we have no data at all regarding the Mallophaga of birds from 

 the west coast of South America 



The authors, however, found that of the 44 mallophagan species 



collected on the expedition 19 were identical with those Kellogg 



had previously studied from North American and Central Ameri- 

 can birds. 



