Page:The Fauna of British India, including Ceylon and Burma (Birds Vol 1).djvu/42



This edition of the Fauna follows its predecessor in beginning with the Passeres. The classification and further division of this Group presents more difficulties than all the rest put together.

Briefly, the Passeres may be defined as follows:—Skull ægithognathous (vomer truncated in front). Sternum with a large spina externa, and no spina interna. Clavicle with expanded free ends. Hypotarsus complex.

Wing lacking the biceps and expansor secondariorum muscles. Thigh muscles having no accessory femorocaudal or abiens muscles present.

Only one carotid—the left—is present. Cæca are vestigial. Oil-gland nude. Wing eutaxic.

The arrangement of the Sub-Orders adopted here is that of Gadow (Bronn's Thier-reichs, Bd. vi., ii. Syst. Theil, 1893). But the subdivision of the Anisomyodi is based on that of Pycraft (P. Z. S. 1905-6-7), his Oligomyodi answering in part to that of Huxley (P. Z. S. 1867).

Having regard to the fact that the main divisions of the Passeres are based on the structure of the syrinx, a brief summary