now considered in detail, and a new key to the families presented, based upon more extended or special study.
CHARACTERS OF THE TRACHEOPHONE MESOMYODI.
Mesomyodian Passeres with (usually) a single pair of syringeal muscles, attached to the middle portion of the bronchial semirings, the syrinx tracheal, the lower end of the trachea consisting of thin, membraneous walls, about six of the usual semirings extremely thin, sometimes obsolete, the bronchi with both outer and inner tympaniform membranes, vibratory tracheal membranes being also present, the few muscles (usually only one pair) wholly lateral (being thus specially modified as a vocal organ ;)[1] feet schizopelmous; tensor patagii brevis passerine.
The Tracheophone Passeres are (excepting the small family Xenicidæ of New Zealand) a purely Neotropical group of birds, though, like many others, entirely absent from the Antillean Subregion. The various members bear a more or less close resemblance in external appearance as well as in habits to certain Oscinine families, though very distinct in their internal structure. Thus, among the Formicariidæ (Antbirds), some forms closely resemble Shrikes (Laniidæ), others Wrens (Troglodytidæ), and others again are strikingly similar to the Pittas (Pittidæ)[2] in form, though lacking entirely the beautiful coloration of the latter. The Dendrocolaptidæ and Furnariidæ embrace species which, so far as external appearance goes, might pass readily for Tree Creepers (Certhiidæ), Thrushes (Turdidæ), or even Larks (Alaudidæ) ; the smaller Pteroptochidæ are conspicuously wrenlike, while some of the Conopophagidæ are not very unlike
Pipits (Motacillidæ). While they vary greatly in size, form, and
- ↑ This peculiar structure of the organs of voice is thus described by its discoverer, Johannes Müller ("Ueber die bisher unbekannten typischen der Stimmorgane der Passerinen" (title incomplete), von J. Müller, Berlin, 1847): "The lower end of the trachea is flattened anteriorly and posteriorly; its walls are thin and membranous and contain extremely fine anterior and posterior half-rings, which are fastened at the sides by long elastic bands. The position of these half-rings is altered by the muscles attached to their sides. In all these birds the cartilaginous pessulus in the furcation of the trachea is wanting, and is replaced by a tendinous strap. The membrana tympaniformis passes over from one bronchus to the other. The bronchi contain half rings only. The membranous wall of the voice organ consists of two thin transparent membranes, of which the inner one is the mucous membrane." By Professor Alfred Newton it is described (Dictionary of Birds, Part iv, p. 940) as follows: "The lower portion of the Trachea consists of thin membranaceous walls, about six of the rings being extremely thin or, as often happens, deficient. Both inner and outer tympaniform membranes exist in the Bronchi as well as some vibratory tracheal membranes. The few muscles, generally but one pair, are wholly lateral. The birds thus furnished are the Tracheophonæ; their voice is very loud, and while it is being sounded the lower part of the throat swells out."
- ↑ This, however, not an Oscinine family, but a member of the Oligomyodean or Haploophone group of Mesomyodi.
