Syrinx of Pitta angolensis (after (lavrod, P. Z. S. 1876, pi. liii), showing the 

 Mesomyodiau o,ttaclunent of the intrinsic muscles at the middle of tbe bron- 

 chial semi-rings. There is only a single pair of bronchial muscles, continued 

 down from the sides of the windpipe, insignificant in size, quite lateral, and 

 terminating by being inserted into the middle of the outer surface of the 

 second bronchial semi-ring. 



All the Passeres of the Old World belong to the Acromyodian 

 group with the exception of three small families, viz. the Phile- 

 pittidcK from Madagascar, the Xenicidce from New Zealand, and 

 the Pittidoi from India, the Oriental, ./Ethiopian, and Australian 

 regions. The Eurylcemidce, frequently associated with these Meso- 

 myodian Passeres, I propose to elevate to the. rank of an Order. 



It follows from the above that all the Indian Passeres, with the 

 exception of the Pittidce, belong to the Acromyodian group. 



The Mesomyodi may therefore be dismissed from further con- 

 sideration with the remark that they are divided info I wo Croups: 

 the Oliyomyodce, with the lower eud of the trachea unmodified ; 

 and the Tracheophonce, with the lower end of the trachea modified 

 to form an organ of voice. The Pittidce fall into the first group, 

 as do also the Philepittidce and Xenicidce. The remainder of the 

 OligomyodcB and the whole of the Tracheophonce occur only in the 

 New World. 



No success has attended the efforts of anatomists to subdivide 

 the Acromyodi into two or more groups by internal characters, 

 and no two naturalists agree in the arrangement and extent of the 

 families of this difficult group. In drawing up ihe annexed 

 scheme of the families that occur in India I have endeavoured to 

 avail myself of those characters which appear to be constant and 

 easy of examination. 



A very useful character to be employed in determining the 

 position of a bird is the number of primaries in the wing; but 

 before this can be used with absolute precision, it is necessary to 

 eliminate by other characters those families some of the members 

 of which possess nine primaries and others ten. Such families 

 are the Dicasidw and Alaudidas. 



