26 



ANATOMY AND PHYSIOLOGY OF 



the part opposite to the cleft elevated into 

 a conspicuous eminence, bounded on its 

 sides by two deep channels, and a hollow 

 of broader but shallower dimensions in the 

 front. To this central conical elevation 

 ]\Ir. Clark has given the name of frog-slay, 

 from some novel notions he entertains of its 

 physiology. Such a bold promontory of 

 horn rising in the middle of broad and 

 deep channels is well calculated to form 

 that dovetailed sort of connection with the 

 sensitive foot, which greatly augments their 

 surfaces of apposition, and establishes their 

 union beyond all risk or possibility of dislo- 

 cation. It is a part which (as far as my 

 observations on it have extended) grows 

 and becomes developed together with other 

 parts of the foot ; and one that is apt to 

 vary in its relative volume in different feet. 

 In front of the frog-stay, the lateral borders, 

 bounding the hollow in the middle, describe 

 a waving line, which, near half-way to the 

 point of the toe, exhibits a dip or impres- 

 sion : this marks the impression of the 

 navicular bone, and is the part immediately 

 opposite to the ' cushion of the frog,' — a 

 coincidence important to be borne in mind, 

 as tending to throw some light on the na- 

 ture of this new-christened structure.* 



" The Sides are the parts by which the 

 frog establishes its union with the borders 

 of the triangular vacuity in the hoof into 

 which it is admitted. Along their superior 

 borders they are transversely lamellated, or 

 rather indentated, in order that they may be 

 fitted to the internal surfaces of the bars, 

 which exhibit a similar structure. 



" The Commissures are the two deep 

 triangular-shaped hollows between the bars 

 and the sides of the frog. It being only 

 the superior borders of these parts that are 

 engaged in their union, their broad, unat- 

 tached parts, below, form the boundary 

 walls of the commissures. Looking into 

 the interior of the hoof, we discover that 

 the commissures, internally, are converted 

 into rounded promontories, similar in ap- 



* In fact, the cushion of the frog appears to be nothing 

 more than a bulge of the part produced by the superin- 

 cumbent pressure of the navicular bone. 



pearance and texture to the one in the mid- 

 dle — the frog-stay — on the sides of which 

 they are rising. In the natural state, 

 the commissures must unavoidably get 

 plugged with dirt, or whatever the animal 

 may happen to tread upon ; a circumstance 

 from w^hich some far-fetched notions have 

 been extracted concerning their use. 



" The Toe or point of the frog is the ante- 

 rior, undivided, elongated portion; that which 

 forms the apex of the pyramid or wedge — 

 the acute or extended angle of the triangle 

 — the only part displaying that prominent 

 or rounded form that would warrant us in 

 using the epithet ' conical ' to the frog. It 

 possesses sohdity of substance, firmness of 

 texture, and luxuriance of growth in an 

 eminent degree ; facts well known to the 

 farrier, who, in paring the foot, seldom fails 

 to make more free with this than any other 

 part of the frog. 



" The Heels or bulbs of the frog are the 

 posterior protuberant parts embraced by the 

 heels of the wall, and separated from each 

 other by the cleft, forming, together, the 

 base of the wedge or triangle. They pre- 

 sent greater depth of substance than the 

 toe, but are of a softer, more spongy tex- 

 ture, and are less resisting and stable, in 

 consequence of being deprived of mutual 

 support by the division of the cleft. Ante- 

 riorly, the heels unite with the lateral promi- 

 nences bounding the cleft ; inferiorly, they 

 present two surfaces of tread to the ground, 

 eivdently designed to take a share in the 

 bearing of the foot ; posteriorly and supe- 

 riorly, they exhibit a bulbous fulness, in 

 consequence of receiving at this part a sup- 

 plementary covering from a production 

 which has been (in the description of the 

 wall) adverted to, under the appellation 

 given it by Mr. Clark, of 



" Coronary Frog-band. — It was there 

 stated, that the coronary groove (the groove 

 or canal in the coronary border of the cutis) 

 broadened considerably as it descended to 

 and turned round upon the heels ; in like 

 manner does the horny band produced by 

 it broaden, and not only grow broader but 

 thicker in substance, and consequently in 



