THE SENSORIAL FUNCTION. 7j 



There is an evident intention in this division of the head into so many bones. 

 When the fuetus — the unborn foal — first begins to have life, that which afterwards 

 iiecoines bone, is a mere jelly-like substance. This is gradually changed into a 

 harder material — cartilage ; and, before the birth of the animal, much of the cartilage 

 is taken away by vessels called absorbents, and bone deposited in its stead. In flat 

 bones, like those of the head, this deposit takes place in the centre, and rays oi radia- 

 tions of bone extend thence in every direction. Then, by having so many bones, 

 there are so many centres of radiation ; and, consequently, the formation of bone is 

 carried on so much the more rapidly, and perfected at the time when the necessities 

 of tlie animal require it. At the period of birth, however, this process is not com- 

 pleted, but the edges of the bones remain somewhat soft and pliant, and therefore, 

 in parturition, they yield a little and overlap each other, and thus, by rendering 

 the birth more easy, they save the mother much pain, and contribute to the safety of 

 the foal. 



The first of these bones, or the first pair of them, occupying the broad expanse of the 

 forehead, are called the frontal bones, a a. They are united together by a most curious 

 and intricate dove-tailing, to defend from injury the brain which lies beneath the 

 upper part of them. Lower down, and where the cavity of the nose is to be defended, 

 their union is sufficient, but far less complicated. Thus, at first starting, there is an 

 evident proof of design, an illustration of that adaptation to circumstances which will 

 again and again present itself in the most interesting points of view. Peculiar 

 strength of union is given where a most important organ is to be defended — the suture 

 is there intricate and laboured. Where less important parts are covered, it is of a 

 far simpler character. 



Few things more clearly indicate the breed or blood of the horse than the form of 

 the frontal bones. Who has not remarked the broad angular forehead of the blood 

 horse, giving him a beautiful expression of intelligence and fire, and the face gradu- 

 ally tapering from the forehead to the muzzle, contrasted with the large face of the 

 cart or dray-horse, and the forehead scarcely wider than the face ] 



Atj^, between the frontal bones, is the pit or cavity above the eye, and by the depth 

 of which we form some idea of the age of the horse. There is placed at the back of 

 the eye, a considerable quantity of fatty substance, on which it may revolve easily 

 and without friction. In aged horses, and in diseases attended with general loss of 

 condition, much of this disappears ; the eye becomes sunken, and the pit above it 

 deepens. It is said that some of the lower class of horse-dealers puncture the skin, 

 and, with a tobacco pipe or small tube blow into the orifice, until the depression is 

 almost filled up. This, with the aid of a bishopped tooth, may give a false appear- 

 ance of youth, that Avill remain during some hours, and may deceive the unwary, but 

 the trickery may easily be detected by pressing on the part. 



These bones, however, are not solid, but a considerable portion of them is composed 

 of two plates receding from each other, and leaving numerous and large vacuities or 

 cells. These vacuities are called the frontal sinuses. They are shown in the following 

 cut. 



