INTRODUCTORY NOTE. 
The matter included in the following pages was written to form part 
of a report upon tbe insects affecting vertebrate animals, which was 
begun as a conjoint work by Dr. Riley and myself. 
Various circumstances having delayed the completion of the report, 
Dr. Riley has requested that this portion be put in print under my sig- 
nature. 
The publication of this portion singly makes me responsible for the 
matter presented, but I wish to acknowledge the many favors received 
from Dr. Riley which have facilitated the work and made it certainly 
better than it could otherwise have been. 
The figures have in most cases been sketched by the author and 
finished under Dr. Riley's supervision by Miss Lillie Sullivan. A cer- 
tain number have been copied from other works, and these will be found 
duly credited in their place. 
Herbert Osbor>\ 
Washington, D. C, 
July 8, 1890. 
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