NEW MALLOPHAGA. 77 



lection of any set of specimens in order that he may 

 weigh fairly the probable accuracy of the host determina- 

 tions and the value of any statements as to relative abund- 

 ance of the individuals of a species, or of the constant 

 or casual occurrence of any parasite species on the in- 

 dividuals of its host species. 



A large number of the specimens upon which the mono- 

 graphs of the order are based were collected from the 

 dried skins of birds in various museums. Piaget has 

 found the museum of Leyden a fertile field for collecting. 

 But it is evident that collecting under such circumstances 

 makes uncertain any generalization regarding the abund- 

 ance of individuals on the host, and the constancy of oc- 

 currence of any certain parasite species on any certain 

 bird species. There is also much likelihood of " strag- 

 gling " and little opportunity to prove or disprove it. On 

 the other hand, in collecting from the newly-killed birds 

 one can practically determine the total parasitic fauna of 

 any bird specimen ; and, where a large series of speci- 

 mens of one bird species is obtained, definite conclusions 

 as to the constant or casual occurrence of a parasite species 

 upon its host can be attained. The collection of imma- 

 ture specimens is practically restricted to collectors from 

 newly-killed specimens because the tender, unchitinized 

 body of the young insect shrivels soon after death; thus 

 the immature insects are rarely found on dried skins. 

 This may account for the absence of references in the 

 European monographs to the immature stages of any of 

 the described species. 



Methods of Collecting and Preserving. 



The methods of collecting are simple. The parasites 



do not leave the body quickly after the death of the host, 



so if there is no opportunity to take them from the host 



in the field immediately after shooting, they may be col- 



