INFERIOR EXTREMITY OF THE HEAD. 71 



contains large numbers of salivary glands in the thickness of the submucous 

 tissue. The connective tissue which unites it to the adjacent parts is sufficiently 

 loose to allow of an abundant serous effusion. 



The free border of each lip is thin and bevelled, lies in contact with its 

 congener, and is the point of continuity between the skin and the mucous mem- 

 brane. 



The adherent border is marked in the interior of the mouth by a gutter 

 at the point of continuity of the mucous membrane with the gums. Externally, 

 it is not delimitated from the adjacent parts, with which it becomes continuous. 



The commissures are the points where the two lips become continuous; 

 slightly round and quite thick, they are perfectly closed in ordinary conditions. 



Their volume appears" much larger in young than in old animals, 

 because the direction of the incisor teeth, upon which their internal 

 face rests, becomes more and more horizontal with the progress of 

 age. Also, the head in old horses seems to be tapering at its inferior 

 extremity. 



The lip, like the nostril, the eye, and the ear, is a most remark- 

 able organ of expression. When it is curled up, relaxed, lowered, 

 elevated, or inclined, we have so many variations which aifect the 

 whole physiognomy. When we study the expression of the horse 

 under the influence of pain, fear, pleasure, or distress ; when we ob- 

 serve his attitude as he attempts to snatch or bite somebody or one of 

 his companions ; when we observe the lips in certain diseases ; when 

 we translate the language of the stallion as he scents the mare, or the 

 animal as he passes through the death-agonies, then can we see how 

 perfect the expression is and how it varies in each circumstance. 



It is well known, also, that the physical qualities are in direct 

 relation with the faculty of expression of which the lip is capable. The 

 horse which is of a sanguine temperament, with a nervous system 

 that is well developed, energetic, and easily stimulated by external 

 causes, presents a high development of this region. The common 

 horse, on the contrary, has a lip which is thin, soft, flabby, immobile, 

 and without expression. The skin which covers it is thick and the 

 hairs long, coarse, and abundant. 



The lips should approximate themselves easily by their free border 

 to keep the mouth constantly closed, in order to avoid a continuous 

 escape of saliva. Nevertheless, it is not always thus, from the fact 

 that the animal is " reined up too high," or that one of the lips may 

 be paralyzed. In the first instance, the mouth remains open from the 

 fatigue of the muscles induced by the unnatural position of the head ; 

 in the second, there is great difficulty in the prehension of food, the 

 constant loss of saliva is deleterious, and the physiognomy loses all its 



