ORGANS OF VOICE AND RESPIRATION. 1Q7 



ORGANS OF VOICE AND RESPIRATION. 



THE air during the act of inspiration in Birds passes through the 

 nasal openings to the Rima glattidis, the opening and closing of 

 which aperture may be very well observed in the expanded mouths 

 of young birds while they are being fed. The rima glottidis forms 

 a longitudinal fissure in the superior larynx, and is generally 

 provided with pointed or obtuse epithelial papillae more or less 

 strongly developed, and frequently arranged in rows that would ap- 

 pear in some measure to supply the place of the epiglottis, which is 

 wanting in the present class ; they offer varieties in the several 

 genera, and are wanting only in the Struthionidae. Occasionally 

 there is found behind the tongue a membranous valve-like fold, as in 

 many Ducks and in the Ostrich ; in some cases this fold has a me- 

 dian lappet, as in Scolopax gallinula, while a thicker dentated fold is 

 found as a rudiment of the epiglottis in Fulica atra. A true epi- 

 glottic cartilage appended to the superior border of the thyroid car- 

 tilage occurs however in a few Birds, as the Swan and some other 

 Natatores and Grallae. 



The Superior Larynx consists of several cartilaginous pieces, 

 which admit of being compared with analogous parts in the human 

 subject, and are constantly ossified in adult Birds. The largest of 

 these pieces is a single bony plate, which forms the anterior part of 

 the larynx, and abuts posteriorly and inferiorly against two lesser 

 elongated and narrow cartilaginous pieces, not united in the median 

 line, which appear at first sight in adult Birds to be separated from, 

 the anterior bony plate, but are blended with it at an early period 

 in young birds. These three bony pieces are the conjoined repre- 

 sentatives of the thyroid cartilage ; the anterior plate is usually in- 

 terrupted by several transverse intervals, that indicate its original 

 formation from the coalescence of a short series of tracheal rings, 

 these last being distinctly perceptible in many cases. Two to four of 

 these rings are generally to be recognised, except in the Parrots, 

 where there is no visible trace of their fusion. Posteriorly and 

 internally the thyroid plate presents a more or less elevated ridge, 

 dividing incompletely the cavity of the superior larynx into two 

 symmetrico-lateral halves. Another process (processus epiglotti- 

 cus Henle) arises from it superiorly, and in many Birds, as Larus, 

 Alca, from its soft and slender condition approaches in character to 

 the epiglottis of the mammiferous animal. Posteriorly, between 



