. Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology, an outline of the structure and classification of birds, and Field ornithology, a manual of collecting, preparing, and preserving birds . oose dry pith in theform of a series of caps or thimbles, sometimes called the soul. These are the remainsof the innermost layer of the inner division of the Malpighian stratum. On
. Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology, an outline of the structure and classification of birds, and Field ornithology, a manual of collecting, preparing, and preserving birds . oose dry pith in theform of a series of caps or thimbles, sometimes called the soul. These are the remainsof the innermost layer of the inner division of the Malpighian stratum. One end of thisquill tapers to its insertion, and is matked by the trace of what was an opening when thefeatlier was growing; this is the umbilicus inferior. The other end of the calamus passesdii-ectly into the rhachis, at a point marked by a little pit, the umhilicus superior, on the underside of the feather (nearest the birds body). The rhachis (Gr. pdxts, rhachis, a spine or ridge)is the direct continuation of the calamus to the tip of the feather, but (lifters in cliaracter, beinga four-sided prism, squarish in cross section, tapering gradually to a fine point: it is less hornythan the barrel, very elastic, opaque, and solidly pithy; it alone bears the vexilla, serving asa midrib between the two vanes for their whole extent. Tlie rhachis is usually grooved length- EXTERNAL PARTS OF BIRDS. — FEATHERS. 85.
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectbirdsnorthamerica
