306 Mr. YannELL on the Organs of Voice in Birds. 
particles of food passing into the windpipe; but the surface near 
the opening is furnished with numerous papillz, pointing back- 
wards, which assist in directing and convey ME food towards and 
into the cesophagus. 
Tas. XVII. Fig. 1. is a representation of the glottis with its 
surrounding membranes.  Fig.2. is a representation of the car- 
tilages forming the superior larynx. The letters, a, a refer to 
the principal cartilage, which, when in its natural situation, lies 
upon the pharyngeal portion, and between the cornua, of the os 
hyoides or bone of the tongue. This cartilage appears to perform 
the double office of the thyroid and cricoid cartilages in the 
higher animals. In substance it is uniformly thin, its shape 
nearly triangular, one angle placed forwards, the lateral angles 
curving upwards to support the base of the arytenoid cartilages 
on its own side. The letters b, b refer to the arytenoid cartilages, 
supported at their base by the lateral angles of the cricoid car- 
tilage before mentioned, and projecting forwards in two narrow 
and thin parallel processes over two-thirds of the orifice formed 
by the curved lateral portions of the cartilage underneath: each 
parallel process forming a slight groove on its superior surface 
by the edges curving upwards. 
The glottis is closed by a pair of molis (Tas. XVII. Fig. 4, 
a, a) extending from the upper portion of the cricoid cartilage 
along the crura of the arytenoid cartilages, upon each outer edge 
of which they are inserted ; and it is opened by a pair of Biede 
arising from the lateral and posterior portions of the cricoid 
te rtilnge; the fibres of which passing over the pair of smaller 
muscles just described, are inserted upon the inner edge of 
each arytenoid cartilage (Fig. 3, b, b). The obvious use of 
these two pair of muscles is to govern the size of the aper- 
ture. Baron Cuvier in his Lecons d' Anatomie Comparée, vol. iv. 
p: 490, says, “ Birds have no arytenoid cartilages ;” but the 
uses 
