. A manual of zoology. 462 MANUAL OF ZOOLOGY which it subsequently protrudes as an elongated feather-ge?-m, its vascular dermal interior being the feather-pulp. The horny substance of the feather is formed from the epidermis of the feather-germ. The feathers do not spring uniformly from the whole sur- face of the body, but from certain defined areas (Fig. 275),. Fig. 275. — Pterylosis of Columha livia. A, ventral; B, dorsal. at pt, alar pteryla or wing-tract; c. pt, cephalic pteryla or head-tract; cd. pt, caudal pteryla or tail-tract; cr. pt, crural pteryla; cr. apt, cervical apterium or neck-
. A manual of zoology. 462 MANUAL OF ZOOLOGY which it subsequently protrudes as an elongated feather-ge?-m, its vascular dermal interior being the feather-pulp. The horny substance of the feather is formed from the epidermis of the feather-germ. The feathers do not spring uniformly from the whole sur- face of the body, but from certain defined areas (Fig. 275),. Fig. 275. — Pterylosis of Columha livia. A, ventral; B, dorsal. at pt, alar pteryla or wing-tract; c. pt, cephalic pteryla or head-tract; cd. pt, caudal pteryla or tail-tract; cr. pt, crural pteryla; cr. apt, cervical apterium or neck- space; fm. pt, femoral pteryla; Im. fit, humeral pteryla; lat. apt, lateral apterium; , spinal pteryla; v. apt, ventral apterium; v. pt, ventral pteryla. (After Nitsch.) the feather tracts or pterylce (, hit. pt, etc.), separated from one another by featherless spaces or apteria (v. apt, etc.), from which only a few filoplumes grow. In the wings and tail certain special arrangements of the feathers are to be distinguished. When the wing is stretched. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmillan Company; London, Macmillan & Co. ,Ltd.
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