260 THE ANATOMY AND 



presents an eminence, to which the extensor pedis tendon is 

 attached {Plate X. ; see Fig 1 . /) ; its sides stretch back 

 into two lateral processes or wings, to the upper surface of 

 which are fixed the lateral cartilages {Plate X. ; see Fig 2 

 . b and c) : its superior surface presents two articular cavi- 

 ties, and its lower is vaulted, and to it is attached the per- 

 forans tendon {Plate X. ; see Fig \ . g) ; while its exterior is 

 covered by the sensitive laminae. It wall be seen to be of a 

 loose texture, with small bony ridges extending from above 

 downwards, favouring the attachment of the sensitive 

 laminae. The navicular bone {Plate X. Fig \ . e ; Fig 2 

 , e) , which in shape is supposed to resemble a boat or shuttle, 

 embeds itself between the wings of the coffin bone, to which 

 it is attached. 



The small pastern bone {Plate X.. Fig I . c), articulates 

 with the coffin and with the navicular bones, to both of 

 which it is united by the capsular and other ligaments. 

 The lateral cartilages are externally convex, and internally 

 slightly concave, their upper surface stretching superiorly 

 beyond the confines of the hoof {Plate X. Fig 2 . b and 

 c) . The lamincB are vascular, and sensitive productions ; 

 possessed of that elasticity which belong to all living matter ; 

 situated round the surface of the coffin bone, and between 

 every two lies their secretion in the shape of a horny lamina, 

 which constitutes part of the inner wall of the hoof {Plate 

 X. Fig 2 . h; Fig 4 . b). The extensor j^edis tendon 

 passes in front of the os corona into the anterior eminence 

 of the coffin {Plate X. Fig 1 ./), and the flexor perfo- 

 rans tendon affixes itself to the posterior of the bony sole 

 {Plate X. Fig I . g). The elastic frog is situated next to 

 this {Plate X. Fig 1 . h ; Fig 2 . a), on which, and on the 

 flexor tendon, the navicular bone rests. The sensitive frog 

 and sole lie under the coffin bone and elastic frog, the horny 

 sole and frog covering them interiorly : while the hoof 

 generally covers the whole of the sensitive parts of the foot 

 {Plate X. Fig 2 . i). 



The hoof is a horny envelopment, secreted from a con- 

 tinuation, although altered state of the cutis (see the con- 

 tinuous white line in Plate X. Fig 1), exactly as the 

 human nail is formed from that which is termed the quick : 

 it is distinctly composed of fibres parallel with each other, 



