156 THE AMERICAN NATURALIST 



[Vol. XLVII 



The Paradiseidse, the radiant birds of paradise, are rep- 

 resented in the list by eight species. 



Finally, the Corvidse, or crows and jays, are repre- 

 sented at present by thirty-two species, abont one ont of 

 ten of the known kinds, of which thirteen belong to the 

 genus Corvus. Both these numbers will be increased 

 when I am able to incorporate in the list the records, 

 already worked but not yet published, of a considerable 

 collection of Mallophaga from the crows and jays of 

 India, sent to me by Superintendant Annandale of the 

 Indian Museum at Calcutta. The Corvidae are provided 

 with a number of parasite species characteristic of the 

 family, such as Docophorus atratus, Colpocephalum sub- 

 csquale, Menopon mesoleucum, et al. This latter parasite 

 occurs on four species of Corvus, two of old world and 

 two of new world range. Colpocephalum subcequale oc- 

 curs on two North American and one European species 

 of Corvus. 



V 



From these examples of Mallophagan distribution 

 illustrating various special conditions of host relations a 

 number of rather important points of significance appear. 

 Of two only, however, which indeed at bottom are really 

 one, shall I speak. First, there is apparent in Mallo- 

 phagan distribution a general faithfulness of parasite to 

 host kind or group of related host-kinds, and this without 

 much reference to geographical conditions. And second, 

 there appears a plain tendency for a single parasite spe- 

 cies to be common to two or more related host species, 

 even though these hosts be so widely separated geograph- 

 ically and so restricted to their separate geographic 

 ranges that all possible chance of contact between indi- 

 viduals of the different host species seems positively pre- 

 cluded. The American and the European avocets do not 

 meet; nor do the American and European coots. Yet 

 the two coots have five Mallophagan species in common, 

 and the two avocets two. The American and European 

 bitterns are both infested by a common parasite species. 



