34 DISEASES OF THE HORSE’S FOOT 
Perioplic Ring, the cells of which have as their function 
the secreting of the Periople, a layer of thin horn to be 
noted afterwards as covering the external face of the wall. 
From the perioplic ring the cushion is separated by a 
narrow and shallow, though well-marked, groove. 
The inferior border is bounded by the sensitive lamina. 
Fic. 17.—Tue Krrarocenous MEMBRANE (VIEWED FROM THE SIDz). 
(THe Hoor REMOVED BY MAcERATION.) 
1, The sensitive lamine, or podophyllous tissue; 2, the coronary cushion ; 
3, the perioplic ring ; 4, portion of plantar cushion ; 5, groove separating 
perioplic ring from coronary cushion ; 6, the sensitive sole. 
The upper portions of the laminz, those in contact with 
the cushion, are pale in contrast with the portions imme- 
diately below, and thus there is given the appearance of a 
white zone adjoining the inferior border of the cushion. 
Widest at its centre, the cushion narrows towards its 
extremities, which, arriving at the bulbs of the plantar 
cushion, bend downwards into the lateral lacune of the 
