PASSEBES O 



IV. In Passerine birds the oil gland is nude. Caeca are 

 present, though small. The atlas is perforated by the odontoid 

 process (Beddard). The young are hatched naked and helpless. 



V. The Syrinx, the vocal organ of birds, attains its highest 

 development among the Passeres. In accordance with the number, 



Base of skull of Corvultur albicollis (White-necked Haven), showing an 

 cegitJwgnathous arrangement of the palate-bones. 



vo., vomcr ; mxp., maxillo-palatine ; lac., lacrymal; pa. , palatine ; sph.r., 

 rostrum of sphenoid ; b.sph., basi-sphenoid ; ptg., pterygoid ; <., quadrate. 



arrangement and attachment of its muscles the Order is sub-divided 

 into : 



(1) The Acromyodi. With the intrinsic muscles of the syrinx 

 inserted into the ends of the bronchial semi-rings. 



