Fig. 1.—Left Ulna Radius of a Specimen of the Turkey Vulture (Cathartes aura.) Outer aspect, showing union three weeks after fracture from a shot from n·45 Government carbine ball. From the author's figure. (The larger bone is the ulna.)usually unite with scarcely any deformity. This is by no means the case in mammals below man, for in them, where the long bones of the limbs are fractured near their middle, or even in the upper and lower thirds, very considerable angularity results upon union—an angularity that in some cases may even equal a right angle, as I once saw in the case of a fracture of the femur in a muskrat (Fiber zibethicus). The specimen exhibiting the fracture in Prof. Cope's collection of fossil birds consists of a portion of some such bone as the humerus from a bird apparently about the size of a medium-sized goose. It is about 4·5 centimetres long, and has been broken longitudinally both through the callus and the shaft, the corresponding piece having been lost. If the piece be from the humerus of such a bird as I have mentioned, it must be from the very middle of the shaft, for it presents no part of the sigmoid curve as seen at either extremity. The walls are comparatively thin, and the medullary canal large. The fracture occurred square across, or at right angles to the axis of the shaft. There is no provisional callus within the medullary canal, but the bone in the neighborhood of the fracture within that tube is roughened, showing the effects of the attempt at repair. Probably the internal provisional callus may have been broken out of the specimen before it was discovered. Externally the fossilized, spongy, bony callus is quite abundant, and has all the appearance of the distal moiety of the callus upon the ulna of the turkey vulture shown in Fig. 1, and was at about that stage when the individual perished. Among existing birds of the group to which I suspect this specimen belonged, as the swans, geese, and ducks, I have known very excellent results follow in the case of the direct simple fracture of the shaft of the humerus. If they be not pursued to the death by the hunter, they usually swim
Page:Popular Science Monthly Volume 42.djvu/702
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THE POPULAR SCIENCE MONTHLY.
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