LARYNX OF MAMMAL FA. 



503 



producing the shrill but tremulous or vibratory scale of notes, 

 sinking to its close, and called the * neigh.' It is peculiar to the 

 group of Eqaidce with callosities on both fore and hind legs and 

 with flowing mane and tail ; the species with callosities on the 

 fore legs only, with stiff erect manes and naked terminally tufted 

 tails, vibrate their vocal cords by currents of air in alternate 

 opposite directions, produced by vigorous acts of inspiration and 

 expiration, with the head and neck held in the position in which 

 such currents can best act upon the larynx ; the sounds so pro- 

 duced are termed the * bray : ' in some species the notes are long- 

 drawn out, e. g. the ass ; in others they are shortened to a kind 

 of ' bark,' as in the S. African striped ass, called, on that account, 

 4 couakka' or s quagga.' 



The thyroid of the Tapir is thicker than in the Horse or Ass, 

 and lies more in the plane of the trachea : the cricoid is less 

 than in them, and has no tubercle on the back part. The 

 arytenoids resemble those of the Horse, but are less hollowed 

 behind. A triangular fibrocartilaginous mass represents the two 

 cartilages of Santorini (fig. 462, k, k, Horse) ; a similar trian- 



gular fibro-cartilage at the anterior 



4(51 



border of the arytenoid represents 

 the cuneiform cartilage, and is con- 

 tinued at its apex into the lower 

 vocal cord ; this is well marked, 

 sharp, and joins its fellow at an 

 acute angle ; the upper vocal cord 

 is very short, but definable. The 

 f ventricle ' is prolonged into a 

 blind oval sac resting upon the 

 inner surface of the thyroid. From 

 the anterior confluence of the lower 

 cords a membranous fold ascends 

 toward the epiglottis, and divides 

 into two semilunar folds which 

 bound small follicular depressions. 



IThe epiglottis resembles that of the 

 Ass ; an opening at its base leads 

 to a curved cavity on each side. 

 In Artiodactyles the wings of 

 the thyroid unite at an acute 

 angle. In the Hog there are no upper cormia : the cricoid, fig. 

 464, f, is broad and thick behind, with a tuberous process on each 

 side. The arytenoids, e, are united at their apices by a i santo- 

 VOL. II r. Q Q 



Mesial section of the Larynx of the Pig (Sus 

 scrofa). cccxx. 



