STRANDED AT LONGNIDDRY. 237 



from 3 to 4 inches, separated the opposite inferior margins from each other. 

 It was filled up by a strong fibrous membrane, which was continuous laterally 

 with the perichondrial investment of the cricoid and its plate-like offshoots, 

 anteriorly with the perichondrium investing the posterior horns of the two 

 arytenoid cartilages, and posteriorly with the membrane which filled up the 

 interval between the ventral borders of the first two cartilages of the trachea. 

 This membrane, which may be called the inferior crico-tracheal membrane, was 

 of great importance as completing the wall of the windpipe on its ventral aspect. 

 The posterior margin of the cricoid was comparatively narrow; the anterior 

 margin possessed at each lateral angle a broad surface for articulation with the 

 body of the arytenoid cartilage, distinct capsular and synovial membranes con- 

 nected the two cartilages. 



Each arytenoid cartilage, irregular in form, consisted of a body and two 

 cornua. The body formed a thick plate of cartilage. The anterior cornu 

 curved upwards and forwards into the lappet-like fold of mucous membrane 

 behind the superior laryngeal opening. The posterior cornu curved back- 

 wards and inwards within the area enclosed by the sides of the cricoid ; it 

 almost reached the mesial plane, where a transverse fibrous ligament connected 

 it by the tip to its fellow. The two posterior horns formed an imperfect hoop, 

 invested by the mucous membrane of the larynx, which was prolonged directly 

 backwards and downwards to form the mucous lining of the laryngeal sac. 

 The free rounded border of the cricoid was connected to the posterior cornu 

 of the arytenoid by the inferior crico-tracheal membrane. A crico-thyroid 

 muscle existed also on each side, and muscular fibres were seen to occupy the 

 position of the crico-arytenoidei postici and arytenoideus. 



The epiglottis contained a bar of yellow fibro-cartilage, which passed back- 

 wards along the axis of the entire structure, to be attached to the superior 

 surface of the middle portion of the thyroid cartilage. In the older animal, 

 from which it had been removed without much injury," 5 - the entire organ 

 measured 25 inches in length, whilst its breadth at the base was about 10 

 inches ; it was thick and massive, and rounded in form at its free end. The 

 fibro-cartilage was covered by mucous membrane, which was prolonged back- 

 ward as the aryteno-epiglottidean folds, and forward as the hyo-epiglottidean 

 fold. When this membrane was removed from the hinder surface of the epi- 

 glottis and its arytenoid connecting folds, a strong aryteno-epiglottideus muscle 

 was exposed, which curved upwards and inwards, decussating with its fellow 

 in the substance of the epiglottis, and obviously was arranged to act as a 



* The other laryngeal cartilages were so much injured during their removal from the adolescent 

 whale, that I was unable to examine them satisfactorily. I may, however, refer to their great size and 

 thickness, more especially of the cricoid and body of the arytenoid. The cartilage was traversed in 

 various directions by very distinct vascular canals. 



VOL. XXVI. PART I. 3 Q 



