one of the sides overlaid with a thin coating of gristle, and 

 covered by a delicate secreting membrane, very hable upon 

 the shghtest injury to become inflamed ; it is unfortunately 

 so placed in the foot, as to be continually exposed to danger, 

 bemg situated across the hoof, behind the cofiin bone, and 

 immediately under the coronet bone,''" whereby it is compelled 

 to receive nearly the whole of the weight of the horse each 

 time, that the ojjposite foot is raised from the ground. 



The cofiin bone t consists of a body and wings, and is 

 fitted into the hoof, which it closely resembles in form ; its 

 textm-e is particularly light and spongy, arising from the 

 quantity of canals or tubes, that traverse its substance in 

 every direction, affbrdmg to numerous blood vessels and nerves 

 a safe passage to the sensitive and vascular parts surrounding 

 it ; while the unyielding nature of the bone effectually pro- 

 tects them from compression, or injury under every variety 

 of movement of the horse. 



In an unshod foot the front and sides of the cofiin bone 

 are deeply furrowed and roughened, to secure a firm attach- 

 ment of the vascular, membranous structure by which the 

 bone is clothed ; but in the bone of a foot, that has been 

 frequently shod, this appearance is greatly changed ; the 

 fvuTows and roughness having given place to a comparatively 

 smooth surface. This change I imagine to be produced by 

 the shoe limiting, if not destroying, the expansive power of 

 that part of the hoof, to which it is nailed ; whereby a 

 change of structure in the membrane itself, as well as ab- 

 sorption of the attaching portions of the bone is induced : 

 * Plate 2, fig. .4. t Plate 2, fig. 2. 



