THE OS HYOIDES. 
405 
nually getting dirt and filth and thorns and insects about his 
muzzle thus brought into contact with the ground, and he must 
have some means of ridding himself of the nuisance. He has it 
in the length and freedom of motion of his tongue. You will 
rarely see the tongue of the horse protruded from his mouth, 
except he has acquired the trick of licking his manger ; but the 
ox is frequently employed in cleaning his muzzle, and his flexible 
tongue will reach even to his nostrils. When two horses are ex¬ 
pressing their mutual friendship, it is by nibbling each other ; 
oxen will stand licking each other for an hour at a time. 
It was to give freedom of the tongue to the one, and to take it 
away from the other, that the ox had no projecting spur, and two 
perfect joints on either side, while the tongue of the horse was 
tied down by this inflexible bone piercing its root, and its freedom 
still more impaired by one joint only being given to the hyoid 
bone. 
The Os Ili/oides i/i the Dog. —Here you will perceive that we 
have not only a deficiency of spur, but also of tubercle. There 
is even a depression in the centre of the body of the bone, and 
there are two shorter cornua on each side. The tongue of this 
animal requires as much freedom as, or even greater than, that of 
the ox; for if he has not to gather his solid foot together, he has 
to lap that which is liquid. 
Of the Swine. —We have here also the hollow instead of the spur 
or the tubercle, for the swine nuzzling in search of his filthy food 
requires considerable use of the tongue. You will observe the 
singular form of the cornua in this animal, the strength of the 
first shorter one, the smaller development of the central one, and 
the slimness and insignificance of the longer one, compared with 
that of any other animal that we have examined. You will ob¬ 
serve likewise that the interposed ligament between the body of 
the bone and the thyroid cartilage (the hyo-thyroid ligament) 
is strangely diminished, the bone seeming closely to embrace 
the cartilage. Of the physiological reason of these differences of 
structure, I confess that I am unable to speak. Veterinarians 
have not yet deemed them worthy of attention. The time, how¬ 
ever, is at hand, when our duty will be better understood and 
practised. 
With regard to the difference of muscular structure I will not 
detain you. You will perceive that the hyoideus magnus in the ox 
has no pulley for the insertion of the digastric, and that the stylo¬ 
hyoid* us is larger and digastric, while in the hog it is, like 
the longer cornu, of comparative insignificance. The genio - 
hyoideus is much more developed in the ox than in the horse. 
