VOICE. 



U95 



lying in front of the larynx. Tracheal 

 length 4 in. ; posterior cartilaginous, an- 

 terior membranous at its laryngeal extre- 

 mity. Arytenoids : superior prominences 

 elongated, flattened, and inclined forwards 

 their inner margins lie in contact; the inferior 



Fig. 911. 



Section of the Tongue, Pharynx and Larynx of the. 

 Porpoise. 



a, pyramidal position of larynx ; e, pharynx ; d, 

 laryneeal cavities laid open, and a bristle is passed 

 though the glottis,/. 



prominences short, but strong. Epiglottis : 

 base springs from the superior margin of the 

 thyroid, to which it is fixed by a cartilaginous 

 union. It is flattened and directed back- 

 wards to unite with the superior prominence 

 of the arytenoids, with which it completes the 

 aryteno-cpiglottic portion of the vocal 

 tube. The diameter of this portion is nar- 

 rower than the rest of the tube, which crosses 

 the fauces, enters the posterior nares, and 

 terminates in the olfactory organs. In its 

 passage it is grasped by a strong sphincter 

 muscle of the fauces, as in the porpoise, e e 

 (fig. 911). Vocal ligaments absent. Aper- 

 ture of the vocal tube, in those which have 

 but one opening, as the spermaceti and 

 bottle-nose whales, grampus, dolphin, and 

 porpoise, transverse ; but in those which 

 have two apertures*, as in the great whale- 



* Hunter remarks that the cartilages of the 

 larynx are much smaller in the bottle-nosed whale 

 of twenty-four feet, than in the piked whale of fif- 

 teen feet. He is also of opinion that the absence of 

 the vocal cord, co-existing with that of the thyroid 

 gland, tends to show that the functions of the 



bone whale, it is longitudinal. Thyroid gland 

 absent. Voice absent, or reduced to a single 

 lowing. Trachea, in Balcenoptera rostrnfa, 

 length 4 in.; posterior cartilaginous, anterior 

 membranous at its laryngeal extremity. 



BIRDS. The vocal organs of birds differ 

 from every other class of animals by the con- 

 stitution of the superior, and by the addition 

 of an inferior larynx. The same acoustics 

 apply, with few exceptions, to all Mammalia, 

 but in birds is required an additional investi- 

 gation. 



The superior larynx of birds is situated 

 immediately below the os-hyoides, to which it 

 is connected by the thyroid membrane, and 

 hyo-aryngeal muscles. Its figure and struc- 

 ture are more uniform than those of the 

 inferior larynx. It is partly cartilaginous, and 

 partly osseous. 



The thyroid cartilage forms the anterior, 

 and part of the lateral boundary of the larynx, 

 and rests upon the first ring of the trachea. 

 Wings, superior margin ascending forwards 

 and upwards, meet each other in the mesial 

 line, where the cartilage terminates in either a 

 pointed, rounded, or flattened projection; in- 

 ferior margin usually horizontal, corresponding 

 to the first ring of the trachea, as in Palmi- 

 pedes, but are excavated in Scansorcs. The 

 posterior margins terminate in two quad- 

 rangular bones, with which the thyroid carti- 

 lage is frequently ossified (and these then 

 become portions of the wings of the thyroid ; 

 the quadrilateral bones, being also oblique 

 angled, are shaped to form a union with the 

 posterior margin of the thyroid, and present 

 horizontal edges above and below, leaving a 

 small triangular space for the cricoid cartilage 

 posteriorly. The cricoid is a small triangular 

 bone, lying on the inside of the posterior edges 

 of the two quadrangular bones ; it supports 

 the two arytenoid cartilages, as in Mammalia; 

 and although it forms a very small portion of a 

 ring, it is yet necessary for the completion of 

 it. These four bony or cartilaginous pieces 

 are most distinct in young birds, and amongst 

 old ones are quite distinct in the Anas do- 

 mesticus and Anas nioffissinnis, but are con- 

 solidated into one in the Scansores, ostrich, 

 and many others. The arytenoid cartilages 

 are long and tapering upwards and forwards, 

 and form by their inner margins laterally the 

 rima glottidis : they are generally ossified. 

 Their external margins are bounded by the 

 thyroid cartilage, and their inner margins 

 form the rima glottidis. 



Epiglottis. In most birds the epiglottis is 

 situated on the internal surface of the thyroid ; 

 it is rudimentary, and is termed the processus 

 epiglotticus : it is generally osseous, but ac- 

 cording to Henle it is leaf-like in the stork 

 and heron ; and in some of the Gallinaceas, as 

 in Slcrna,Rafliis,and Larus, it is thin, flat, and 

 flexible, as in Mammalia. 



Rima g/ottidis. The form of this chink 

 in a state of repose is triangular, the apex 

 being directed backwards: it is bounded an- 



latter are in some manner associated with those of 

 the former. 



.5 C 4 



