54 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



and individuals above mentioned the writer is under deep ob- 

 ligations for the use of this material. 



Next to the data obtained directly from this splendid series 

 of specimens, the writer is inclined to give high place to the in- 

 formational value of the field work incidental to its collection, 

 in much of which he took an active part. The ideal material 

 upon which to base conclusions as regards relationships and 

 distribution consists of specimens in freshly acquired autumnal 

 plumage, taken at the exact localities where the birds were 

 born. As we have not usually any means of knowing the 

 exact birthplace of a bird, the results of our studies must often 

 depend upon assumptions based largely upon one's knowledge 

 of the species in general and its usual mode of life. Just here 

 is where it would seem that experience and information 

 acquired through extensive field work would be invaluable 

 in aiding in an analysis of the facts presented by series of 

 skins — facts often in apparent conflict. The man who works 

 from the dried skin alone is handicapped more than he usually 

 realizes. In working out the relationships and distribution 

 of closely connected forms, a labor entailing the handling of 

 large series, anomalous specimens are frequently encountered, 

 calculated to lead one astray. Some knowledge of the country 

 and climate, the physical surroundings of the species in gen- 

 eral, will frequently give a clue to the explanation, while inti- 

 mate acquaintance with the bird in life will enable one, to a 

 certain extent, to imagine himself in the bird's place and figure 

 out what, under given conditions, is most apt to occur. The 

 life history and habits of the species in general, the faunal 

 complexion of its usual habitat, the nature and extent of vari- 

 ation in the individual and in the race, are all factors of prime 

 importance, and are all to be learned in the course of field 

 work, some of them in no other way. It is not enough, be- 

 cause a specimen bears a superficial resemblance to a race geo- 

 graphically placed more or less remotely from where it was 

 taken, to place the said specimen with such race. In the 

 writer's opinion, this has been done but too frequently in late 

 years, resulting in extraordinary extensions of ranges of cer- 

 tain subspecies without due justification. Familiarity with the 

 birds in life should serve as a most excellent check to such 

 hasty conclusions. 



