LIFE-HISTOR 



OK 



IRDS 



OF EASTERN PENNSYLVANIA. 



C H A 1 ' T E R I . 



Subclass I. Aves Aereae, or Ixsess^res. 

 cr: Mrds or f lurchers. 



OF the three primary divisions constituting the 

 clas> .--lyes, the above ranks as lirst in importance 

 and highest in position, and embraces all existing 

 species down to the c/ L ; or gallinaceous birds. 



Without entering into a full definition of its ex- 



< ^ 



ternal characters, suffice it to say, that with rare 

 eeptions, the toes occupy the same plane and 

 touch the same support throughout, thus adapting 

 them for grasping or perching. The members of 



this extensive irroup are now usually placed in rive 



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orders of which the First is the 



Order Passeres. (Perchets proper. 

 The lo\v insertion of the hind toe and its length; 

 its great power of opposibility to the front toes. 

 and the superior mobility of the same which is 

 secured by the separation of its principal muscle, 

 from that that Ilexes the other toes collectively, 

 perfectly adapt the feet for grasping. The hind 

 toe is ever present and never directed anteriorly 

 or laterally. 'I tic feet are never zygodactyle, syn- 



f A 



