PHYSIOLOGICAL SERIES. 



some they are continued down the wing, communicating with the 

 ulna and radius ; in others they reach even as far as the pinions. 

 The ostrich, however, is an exception : " [i. e. has no air even in 

 the humerus.] Hunter, On the Animal (Economy, 4to, p. 92. 



Hunterian. 



Ilmnerus of an Eagle, showing the common lamellae well developed 

 on its medullary surface, but only slightly on its periosteal. A 

 condition usually present in air-containing bones. Trans, sect. 

 X 20. 



A. 193. The os bumeri of si Silk-fowl (Gallas fernigineus, 

 var. mono] longitudinally bisected, to show the cavity 

 for containing air, and the passage by which it enters, 

 indicated by a bristle. 0. C. 213. 



" The bones which receive air are of two kinds : some, as the 

 sternum, ribs, and vertebrae, have their internal substance divided 

 into innumerable cells ; whilst others, as the os humeri and the os 



