48 HORSESHOEING. 



tective layer (Fig. 29, d) is the thickest, strongest, and most 

 important of the three layers ; it forms the principal mass of the 

 wall, and is developed or secreted by the coronary band, which 

 fits into the coronary groove. There are in the coronary groove 

 a great number of small, funnel-shaped openings into which 

 project the horn-producing villi or papillae of the coronary band. 



Fig. 29. 



Ji 



The outer wall of the hoof has been removed by cutting vertically through the middle of 

 the toe, down to the upper surface of the sole, then horizontally backward into the quarter, 

 and, finally, upward through the quarter : a, periopllc horn-band ; 6, coronary groove ; it 

 turns inward and forward at c to form the upper border of the bar ; A, surface of section of 

 the wall at the toe ; d', at the quarter ; e, surface of horizontal section of the wall near its 

 lower border ; /, keraphyllous layer of the wall ; at/' it turns forward and inward to cover 

 the bar ; /", homy leaves standing free and passing insensibly into the white horn of the 

 middle layer or true wall ; g, homy sole ; A, white line ; j, small horn-spur in middle of toe ; 

 k, part of homy irog which is in intimate union with the upper edge of the bar ; I, frog-stay 

 of horny frog ; it divides the trough-like depression of the upper surface of the frog into m, 

 the two upper channels of the frog. 



(3) The inner layer or keraphyllous layer (Fig. 29,/) consists 

 of prominent, parallel horn-leaves lying side by side over the 

 entire inner surface of the middle layer of the wall, and continu- 

 ing beyond the buttresses to the ends of the bars (Fig. 29, /'). 

 This layer of horn-leaves (keraphyllous layer) has in a general 

 way about the same shape and arrangement as the layer of fleshy 

 leaves (podophyllous layer) which secretes it; for the horn- 

 leaves fit in with the fleshy leaves in such a way that every 

 fleshy leaf is embraced by two horn-leaves, and every horn-leaf 



