Birds and Birding's Guide to:
Watching THE SPARROW-LIKE BIRDS
Sparrow habitat
As a provisional expedient, largely in the interest of convenience and pending fuller knowledge, Mr. Ridgway proposes to designate the”families”of Garrod as”superfamilies,”and to retain the term”family”for”such groups of genera as can be trenchantly separated from all others,”that is, for the groups ordinarily recognized as families.
It is not deemed necessary in the present connection to go into a history of the attempts that have been made to satisfactorily classify the Passeriformes, especially in view of the fact that the anatomy and structure of a great number of forms, sometimes embracing whole”families,”are practically unknown, and until this knowledge is somewhere near complete all classifications of the group must be regarded as more or less provisional and tentative.
Passerine birds are in general of small or medium size, with variously shaped wings in which there are nine or ten primaries, the outermost being frequently rudimentary and nearly or quite concealed, nine secondaries, and usually twelve (rarely ten or fourteen) tail-feathers. Of the numerous structural characters it may be mentioned that the feet are four-toed,1 the first toe (hallux) being on the same level as the others and directed backward, while the second, third, and fourth toes are directed forward; the muscles presiding over the small toes are also peculiar, but need not be here described. The skull is aegithogna-thous, the basipterygoid processes absent, only the left carotid artery present, and the metasternum is usually two — rarely four — notched, while the oil-gland is naked and the caeca present, though usually small. The muscles of the syrinx or the voice organs exhibit a peculiar structure and, as will be shown subsequently, serve as a means of defining several of the great groups.