BIRDS OF ILLINOIS. 



In the following catalogue are included only those species which 

 undoubtedly occur at the present time, and those of whose for- 

 mer occurrence there exists reliable evidence. In strict accuracy, 

 Campephilus principal-is, Conunis carolinensis, and Ajfija ajaja 

 might with propriety be excluded from the regular list and in- 

 cluded in a special category. I have decided to retain them, how- 

 ever, for the reason that any doubt which may now exist concern- 

 ing their present or very recent occurrence can be supported by 

 merely negative evidence, based upon extremely meager data ; while 

 my experience relating to other southern species, resulting from a 

 personal, though by no means thorough, exploration of localities 

 more than 100 miles north of Cairo, leads me to expect interesting 

 discoveries (some of them, perhaps unanticipated), from careful ob- 

 servations in some of the more secluded portions of the extreme 

 southern counties of the State. It is not at all impossible that 

 in these fastnesses, the above mentioned species may still exist. 



The classification and nomenclature followed in the present work 

 are those adopted by the special committee of the American Or- 

 nithologists' Union, and used in the official check-list of the Union, 

 now being printed. As to the classification, however, I have re- 

 versed the sequence of families and higher groups, preferring to 

 commence, as has been customary, with the Thrushes. 



