58 ANATOMY OF A CHELONIAN. 



Larynx and Hyoidean Apparatus ; the description of the 

 latter has already been given (57). 



a. The framework of the larynx is composed of 

 three cartilages : a posterior large, circular 

 piece (crico-thyroid), and a pair of smaller {ary- 

 tenoid) articulated with its anterior margin. 

 The crico-thyroid cartilage fits closely into the 

 concavity at the back of the body of the hyoid, 

 and is thin and membranous in the middle of 

 its convex anterior surface. The arytenoids 

 bound the sides of the aperture {aditus laryn- 

 gis) which lies at the base of the tongue (4, c). 



149. Inflate the lungs fully from the cut end of the 

 windpipe, and then ligature the latter to prevent the 

 escape of the air. Note : 



a. The position of the Lungs, on either side of the 

 vertebral column, in the hollow of the cara- 

 pace. 



b. The layer of pleuro-peritoneum, which covers 

 them and bends them down to the bones pretty 

 closely in front, but leaves their posterior ends 

 free. 



c. Through the serous membrane, a thin muscu- 

 lar stratum (diaphragm) may be seen, forming 

 a -sheet all over the lung, but thicker in front 

 than behind and dorsally than ventrally. 



d. Pushing one lung aside, divide the diaphragm 

 close to the vertebral column, and dissect out 

 the organ. As the lung is removed, its en- 

 veloping muscle will be seen to arise from the 

 necks of some of the ribs, from the vertebral 



