262 List of Birds Cumberland County, Penn. 
of particular sections. 'They too were almost constantly travel- 
ling, and of course could no ertain as much respecting the 
periods of migration at particular places as can be done by more 
1d to glean in the field of 
knowledge where their predecesso: ve reaped so rich a har- 
speak) of the ornithology of that America north of the 
Gulf of Mexico, but many blanks r to be filled up; much — 
still depends upon local observ 
gathered by observers of small distr ricts—men who have the ob- — 
is in Great Britain. On ‘ia importance of this mode of obser 
vation, Swainson and Richardson, in their admirable work on 
the zoology of British America, remark : 
“The discovery of the laws which regulate the distribution of | 
species on the face of the globe being one of the most important | 
ends of the publication of local faunz, the scanty contributions i 
of facts that we have been enabled to make are thrown for the — 
greater facility of reference into a tabular form. The new world — 
is peculiarly adapted for researches of this kind; its two extrem 
ties, and almost every intermediate zone are accessible, and itis 
to be hoped will hereafter be minutely investigated for the pur 
pose of natural science. When accurate lists of the resident 
birds in each region, and of the summer and winter visitors are 
obtained, many highly interesting and unexpected deductions — 
will doubtless be made, and much theoretical reasoning exploded. — 
The Prince of Musignano has performed a great service to science 
by furnishing such a list for the neighborhood of Philadelphia.”— 
Fauna Boreali Americana, Introduction, p. 17. 
Much too may be done in the way of correcting mistakes into 
which our ornithologists have fallen for reasons above stated. 
Many birds spoken of by Audubon, our latest writer, as “ eX- 
tremely rare” in the United States, have been found to be very 
common with us, and others supposed not to visit Pennsylvania, 
are frequently met with. We might cite instances, but the list 
will show facts. of this nature. Nor need any young observet 
despair of finding what is even new, as the writers of this papet 
have procured two species within the narrow limits of their field 
which were previously unknown to science, and descriptions of 
