ANATOMY. 55 



membranes, or laminae, cover all the front and lateral surface 

 of the coffin bone ; at the extremity of which they turn off 

 at an acute angle, stretching forward to the side of the sen- 

 sitive frog : here they form what have been termed the sensi- 

 tive bars. The laminae are elastic, and are said to be about 

 five hundred in number. These laminae are received between 

 corresponding laminae in the hoof; but there is a material 

 difference between them. The laminae of the hoof are void 

 of sensibility ; those of the coffin bone are very sensitive. 

 These two kinds of laminae form the connecting medium 

 between the hoof and coffin bone ; and so strong is their 

 union, that it is found impossible to separate them without 

 tearing or stripping off the sensitive laminae from the coffin 

 bone, unless the foot be placed in water for some time before 

 it is attempted. The extensor tendon (figure r,) is fixed, or 

 inserted, into the upper and front part of the coffin bone. 



The sensitive frog resembles a wedge ; its point is to- 

 wards the- toe, whence it becomes gradually wider and larger : 

 it is divided by a cleft in its centre, towards the hind part. 

 The frog is made up of cartilaginous and fatty matter, and 

 possesses considerable elasticity. Its fore part rests on that 

 part of the flexor tendon which passes over the navicular 

 bone, and on that which is inserted into the coffin bone. 

 From this part its cleft or division commences ; only a small 

 portion, therefore, of the sensitive frog rests on the coffin 

 bone and flexor tendon. The wide part of the frog projects 

 considerably behind these, forming the bulbs of the heels, 

 and, taking a turn forward, is blended with a ligament called 

 the coronary. At its widest or posterior part, there is a con- 

 siderable distance between the sensitive frog and the flexor 

 tendon, the intermediate space being filled up with an elastic, 

 fatty kind of matter. By this contrivance the frog is capable 

 of considerable motion when it receives the pressure of the 

 horse's weight, which it must do when its horny covering is 

 in contact with the ground. The sensible bars are formed 

 by an inflection of the sensible laminae, when they arrive at 

 the heel, whence they pass obliquely forward to the sides of 

 the sensitive frog. 



