ORGANS OF RESPIRATION. 569 



inner margins parallel and approximated, they commonly 

 present, at their tapering anterior ends, the small capitula 

 santorini, which are attached to their apices by distinct 

 articular surfaces, and ligamentous fibres. The capitula are 

 merely continuous, curved, terminal processes of the 

 arytsenoid cartilages in the ruminantia and solidungula, as in 

 the lower classes, and become distinct cartilages in the higher 

 mammifera, where we observe also, for the first time, two 

 small detached cuneiform cartilages lying between the folds of 

 the mucous membrane, the li 'g amenta aryepiglottica, extending 

 from the arytsenoid to the epiglottis. The highly elastic 

 fibro-cartilaginous epiglottis, rising upwards from the ante- 

 rior and superior part of the thyroid, and capable of covering, 

 during deglutition, the entrance of the glottis, is now almost 

 always distinctly separate from the thyroid cartilage. In 

 the cetacea, however, the epiglottis, as shown by Rapp and 

 Henie, is still a mere process continuous with the thyroid 

 cartilage, as in the lower vertebrata, and is in the dolphin and 

 porpise, a thick firm cartilaginous mass, almost destitute of 

 its usual elastic tissue. 



As we ascend in the vertebrated classes, the distance be- 

 tween the arytsenoid and the thyroid cartilages increases, 

 and the connecting mucous fold, the lig amentum aryepiglotti- 

 cum, on each side becomes, in proportion, more expanded 

 over the entrance of the larynx, and now affords space for 

 the development of the cuneiform cartilages, which are not 

 found in inferior classes. The upper and lower pair of vocal 

 ligaments, or chorda vocales, and the intervening ventricula 

 morgagni, are found in almost all mammiferous animals 

 above the cetacea. The inferior vocal ligaments of mamma- 

 lia are the analogues of those of reptiles, and principally 

 form the rima of the glottis. 



The three laryngeal muscles of birds and reptiles, are 

 represented by three groups of muscles in mammalia. The 

 hyo-, crico-y and sterno-thyrioidei muscles, He in front, and the 

 two last of these represent the thyrio-tracheales of birds ; and 

 the glosso-epiglotticus of mammalia is regarded by Henle as 

 only a fasciculus detached from the hyo-thyrioideus, as the 

 epiglottis here represents merely the anterior point of the 

 thyroid cartilage of lower tribes. The cricoarytaenoidei postici, 

 ascending from the cricoid to the arytsenoid cartilages in 

 mammalia, (where we have already seen that the lateral 



