630 THE VALVULAR ACTION OF THE LARYNX. 



cord. The true cord recurves at its free margin in such a 

 manner that with its fellow it could exert a valvular action 

 which would seem to be sufficient to prevent the exit of air, 

 and in the expiratory movement it vibrates with the impulse 

 of the passing air. Cuvier* has shown that there is neither 

 ventricle nor false cord to be found in the glottis of the 

 Bradypus. 



Class III. — Man and the greater part of Ungulate mammals 

 are to be referred to this class, though others have the caver- 

 nous glottis which is embraced in the fourth and final division. 



Here the vocal cords are not only well developed and possess 

 a free border more or less fine, while each is capable of 

 advancing to meet its fellow of the opposite side in the median 

 line, but there exists above the true cords a second pair of 

 analogous folds, less adapted to phonation, and between these 

 projections one recognises a fossa, bilocular but not communi- 

 cating with a sac or cavern. This structure is found in the 

 Carnivora for the greater pait, but this group has many varia- 

 tions amongst its members. In the Dogf {Cants domesticus) the 

 larynx is very large. The true cords are well developed and- 

 broad. They are capable of being bulged to a considerable 

 extent when air distends the ventricles, which are very deep, 

 and ascend a considerable distance along the inner surface of 

 the thyroid. The false cords are neither strong nor prominent. 

 Wolft^ testifies to the strength of the cords of this animal, and 

 mentions that the ventricle is deeper at its extremities than in 

 its middle part. Caiiis lupus.^ — The ventricles of Morgagni 

 are large and deep. In the different species of the Genus Felis 

 the false cords are very prominent and well detached from the 

 walls of the larynx. They are attached directly to the aryte- 

 noids, and at their point of juncture, under the epiglottis, they 

 form a small vault-like attachment. In the Lion|| the true 

 cords are neither so free nor their borders so trenchant as in 

 the Dog ; they are, in fact, thick, and but slightly prominent. 

 The superior part of the larynx is dilated. There is no 



* Ibid., p. 790. t Milne-Edwards, p. 415. 



X Wolff, Dissertatio Anatomica, p. 10. § Op. cit.f p. 10. 



)| Milne-Edwards, p. 445. 



