POLIOPTILA CCERULEA : GNATCATCHER. 79 



sonal observation, from the published experiences of 

 others, or elsewhere. 



Dr. Brewer's attitude in the case is defined in the 

 following quotation from the preface of his list : " It 

 has been my sole aim to furnish a list that shall be 

 reliable so far as it goes. I may have omitted some 

 that are entitled to a place. Be it so ; I had rather 

 omit ten that may be found than retain one that never 

 has been." 



My own position, I am glad to say, was different. 

 Like my collaborator in the same field, I aimed to 

 furnish a list that should be reliable ; but I also aimed 

 to cover the whole ground, so far as the data at my 

 command enabled me to do so. I therefore compiled 

 a list which, my critic is good enough to say, "is re- 

 markable for the laborious research and investigation 

 it displays, and is by far the most complete catalogue 

 we have [1875]." In all doubtful cases I searched the 

 published records with care for evidence ; I admitted 

 no species that that testimony did not seem to warrant. 

 As a part of the evidence bearing on such cases, I ad- 

 mitted and made use of our actual knowledge respect- 

 ing the geographical distribution of species, and the 

 composition of the local Avi-faunae into which the East- 

 ern Province is divisible — a source of information 

 which my critic ignored entirely, and the significance 

 of which he seems never to have had the wit to grasp. 

 I hold that logical deduction from certain known facts 

 may be a positive and decisive kind of knowledge ; 

 and that the mental processes concerned are strictly 

 scientific. However satisfactory to himself Dr. Brew- 

 er's modes of thought may have been, my own are 

 worth more to me. I enjoy and make use of other 



