146 THE AMERICAN NATURALIST [Vol. XLVII 



world. And although each bird has its own stretch of 

 coast mountains, the range of each overlaps that of some 

 other. The individuals of all these bird species, except 

 the last named, are few and solitary in habit, resting and 

 nesting in inaccessible mountain places, but meeting a 

 few of their kind occasionally at common table around 

 some dead or dying animal. Turning now to the para- 

 sites of these lonely birds, we find one species, the well- 

 marked, rather large Lipeurus assessor common to all 

 four vulture species. But assessor has been taken from 

 the wide-spread turkey vulture only in Panama, i. e., 

 within the range of the king vulture. Lcemobothrium 

 delogramma is also found on both the king and the turkey 

 vultures, but has been taken from the latter host again 

 only from Panama specimens. The king vulture and 

 Californian condor, whose ranges overlap in Mexico, have 

 one parasite species, Menopon fasciatum, common to 

 both. These are the only cases of commonness of Mallo- 

 phagan species to two or more of these great vulture 

 kinds. And all are pretty well parasitized, seven Mallo- 

 phagan species being recorded from the king vulture, five 

 from the South American condor, five from the North 

 American turkey vulture, and two from the Californian 

 condor. It is well to keep in mind, in noting this rather 

 abundant parasitization, that the feeding habits of the 

 birds give some opportunity for the straggling of para- 

 sites from other bird or mammal kinds, serving, in the 

 persons of moribund or just dead individuals, as prey. 

 It is therefore indeed important to note that no mammal- 

 infesting Mallophaga have been taken from any vulture, 

 despite the excellent chances for such straggling. Per- 

 haps the difference between a mammal and a bird host is 

 too great to permit a parasite adaptively specialized for 

 life on one to persist successfully on the other. Or per- 

 haps there is a physiological antipathy, a negative chemo- 

 tropism, too strong to permit the straggling. Yet I re- 

 call that in my days as a bird-collector and maker of 

 skins, I repeatedly had the annoyance of discovering 



