No. 555] SPECIES-FORMING OF ECTO-PARASITES 149 



sented by four species, on all five in my list. Nitzschia 

 pulicaris is found on one old world and two new world spe- 

 cies. The humming-birds are not badly parasitized, 

 although three Mallophagan species have been recorded 

 from a single one of these tiny host kinds. They are 

 especially infested by the Mallophagan genus Physosto- 

 mum, although species of this genus occur on several 

 other passerine bird hosts. 



The trogons, order Trogones, are represented in the 

 host list by two species, infected by two Mallophagan 

 species, both of the genus Nirmus. The Coccyzes, or 

 cuckoos, represented by twenty-three species, have usu- 

 ally but one, although sometimes two or three Mallo- 

 phagan kinds to a host species. And this condition of 

 slight parasitization is also true of the five species of 

 toucans and barbets, order Scansores, included in the list. 

 Docophorus latifrons is recorded both from the common 

 European cuckoo and, in varietal form, from the common 

 American cuckoo. 



The order Piciformes, the woodpeckers, is represented 

 in the list by twenty-six species, each carrying but one to 

 two or three Mallophagan kinds to its discredit. The 

 woodpecker genus Dendrocopus is represented by six 

 species of which five belong to the new world and one to 

 the old world. Docophorus superciliosus, described from 

 the old world species of Dendrocopus, occurs also on one 

 of the new world species and also on another old world 

 woodpecker of different genus. One of my Western 

 American Mallophaga species occurs on three wood- 

 pecker kinds in California, one in Baja California and 

 three in Costa Rica. It seems to be a pervasive parasite 

 of American West Coast woodpeckers. Of the seven 

 host species from which it is recorded three belong to the 

 one genus Melanerpes. 



The order Eurylaemiformes, or Malayan broadbills, is 

 represented in the host list by one species parasitized by 

 two species of Mallophaga, while the order Menuri- 

 formes, the beautiful lyre-birds of Australia, three living 



