592 



ANATOMY OF VERTEBRATES. 



prominent ; above them are the orifices, c, e, of the deep ' ventri- 

 cles ': the upper cords are barely definable. The epiglottis, 

 ib. a, is a longish triangle with the apex entire and antroverted, 

 the base medially cleft by the so-called ' snlcus,' ib. d ; and pro- 

 dnced into two processes ( ( cornna ' of Casserius). Between the 

 commissure of the lower cords, ^7, y, and the epiglottis is an oval 

 cavity, c, above which is the ' semilnnar ridge' or { membrane,' b. 

 In the Ass, the wings of the thyroid unite anteriorly at a 



rather obtuse angle : the cricoid 

 resembles that of the Horse : it 

 is similarly cleft and divaricated 

 in fig. 463. The crico-thyroid 

 interspace is relatively less than 

 in the Horse. The epiglottis, a, 

 is a more equilateral triangle 

 than in the Horse, with the apex 



462 



k 



463 



L-irynx of the Horse laid open, cccxx. 



The Larynx of the Ass laid open, cccxx. 



less acute : it is perforated by two apertures, ib. c, c, leading to 

 two ( sacculi ' continued upon part of the inner surface of the 

 thyroid. Between the apertures is the arched recess, ib. />, in 

 which the lower vocal cords, d, d, are inserted ; these arising 

 behind from the bases of the arytenoids. 



The voice of the horse under sexual or other pleasurable excite- 

 ment is due to movements of the vocal cords through forcibly 

 expired air, but with short intervals or interruptions of the current, 



