FROG 547 



the wall, the union between the two being very intimate, through 

 the intervention of homy matter. The inner border represents 

 a deep cut or notch, in the form of the letter V, and is related 

 with the bars, excepting at the narrow part, where it is bounded 

 by the frog. The two angles uniting the outer and inner circum- 

 ferences correspond to the heels, and are received between the 

 wall and the bars ; this part of the sole covers the region which 

 is most liable to injuries, especially to bruises or corns. 



FROG. 



The frog is the prominent, somewhat pyramidal mass of 

 spongy horn lodged between the bars, and filling up the trian- 

 gular space. It has four surfaces, a 

 base, and an apes. The inferior or 

 external surface is very irregular, and 

 presentsalongitudinal triangular cavity, 

 which varies in breadth and depth, 

 being broadest and deepest in well- 

 formed' feet. This cavity is the cleft 

 of the frog, boundmg which are two 

 sloping projections or branches, which 

 unite at the apex of the frog anteriorly, 

 and diverge posteriorly where they join 

 the heels. The superior or internal 

 surface is also very irregular, but ex- 

 actly the reverse of the inferior ; where 

 the one is hollow the other has a pro- 

 jection, and vice versa. It presents over 

 its whole surface numerous small fora- 

 mina, into which are inserted the vascu- 

 lar or secreting papillae of the sensitive frog, likewise' a triangular 

 excavation, which is divided posteriorly into two lateral gutters by a 

 long projection or elevation, corresponding to the cleft on the outer 

 surface. This somewhat conical eminence is called the frog-stay, 

 and it assists in establishing a firm union between the horny and 

 sensitive frogs. The lateral surfaces incline obliquely from 

 above downwards, and from without inwards. In their upper 

 third they are firmly united to the ' external surface of the bars, 

 and anteriorly, to the notch in the sole. Between the inferior 



Fio. 212. 

 Solar aspect of the hoof, a a, Bars ; 

 6 b, Solar border of wall ; c c, Line of 

 union between wall and sole ; d, In- 

 ferior aspect of sole ; d' d', Posterior 

 branches of ^ole ; e, Cleft of the frog ; 

 e' e*, Lateral segments of frog ; //, 

 Bulbs of the frog; g. Point of the 

 frog. 



