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THE POPULAR SCIENCE MONTHLY. 



brates usually unite with scarcely any de- 

 formity. 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 mid- 

 dle of the shaft, for it presents no part of 

 the sigmoid curve as seen at either extrem- 

 ity. The walls are comparatively thin, 

 and the medullary canal large. The frac- 

 ture occurred square across, or at right 

 angles to the axis of the shaft. There is 

 no provisional callus within the medul- 

 lary canal, but the bone in the neighbor- 

 hood of the fracture within that tube is 

 roughened, showing the effects of the at- 

 tempt at repair. Probably the internal 

 provisional callus may have been broken 

 out of the specimen before it was discov- 

 ered. 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 vul- 

 ture 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 



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