. The biology of birds. Birds. FLIGHT 83 These four types of wing are analogous, for all of them are used in actively striking the air. But the wings of insects, which originate as hollow outgrowths from the dorso-lateral regions of the two posterior segments of the thorax (mesothorax and metathorax), are not in any way comparable, as regards development or structure, to the wings of Pterodactyl, Bird, and Bat which are transformed fore-limbs (and rather more in Bats). This is expressed by saying that the wings of insects are analogous but not homologous with the other wings. On the other hand
. The biology of birds. Birds. FLIGHT 83 These four types of wing are analogous, for all of them are used in actively striking the air. But the wings of insects, which originate as hollow outgrowths from the dorso-lateral regions of the two posterior segments of the thorax (mesothorax and metathorax), are not in any way comparable, as regards development or structure, to the wings of Pterodactyl, Bird, and Bat which are transformed fore-limbs (and rather more in Bats). This is expressed by saying that the wings of insects are analogous but not homologous with the other wings. On the other hand, if. MC1 Fig. 21.—Skeleton of bat, creeping, sc, scapula or shoulder-blade ; CL., clavicle or collar bone ; h., humerus or upper arm ; R., radius of fore- arm ; MCI, metacarpal of the thumb (th.) ; , metacarpal or palm bone of second digit; f., femur, or thigh bone ; AC, special heel bone. we keep to the main part of a bat's wing, we may say that the wings of Pterodactyl, bird, and bat are both homologous and analogous with one another, being transformed fore- limbs and organs of true flight. If we compare any of them with our own fore-limb, we see a general similarity in structure and mode of development, but there is no analogy. These distinctions, first made clear by Sir Richard Owen, are not mere pedantries, but enter deeply into the interpretation of organic structure. Let us take Sir Richard Owen's examples :—. 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 Thomson, J. Arthur (John Arthur), 1861-1933. New York : Macmillan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbirds, bookyear1923
