282 PEOr. W. B. BBNHAM ON THE [Apr. 2, 



omitted to notice a fold — sufficieatl_y large, according to these 

 authors, to be drawn over tbe aditus laryngis — if it had existed. 



The drawings given by these authors are small and indistinct, 

 and from an inspection of them I was inclined to regard this 

 " fold " as the epiglottis itself ; but their account in the text is 

 quite precise, and from the size of the " fold " in the adult it 

 is remarkable that it does not exist in the young. 



The general form of the larynx is shown in figs. 1, 2, 3, as seen 

 in various aspects. It is of greater diameter from side to side 

 than in the dorso-ventral direction, and the aryteno-epiglottid 

 apparatus is relatively short, as compared with the long tube 

 in the Odontocete. 



The base of the larynx passes gradually into the trachea, the 

 rings of which are incomplete on the ventral surface. 



The windpipe is, of course, very short, aud thei'e is no " third 

 bronchus" (nor is there in Balcetta), snch as will be seen in Cogia. 



It will be convenient to describe the cartilages first, and then 

 refer to the muscles connected with them. 



The Cartilages. 



In dealing with the topographical relations, the larynx is 

 supposed to be still within the body of the animal, which is in its 

 natural position, back upwards. 



The thyroid cartilage consists of a distinct body and paired 

 posterior cornua. The body is a transverse, narrow band, i. e., it 

 has a very short antero-posterior diameter ; its anterior margin is 

 concave, its posterior convex, but with a median V-shaped notch. 

 At the extreme right and left extremities, where the body becomes 

 continuous with the cornua, the anterior margin is thicker and 

 more prominent than elsewhere ; the ridge-like tubercle so formed 

 probably represents an anterior cornu ; just below it is inserted 

 the sterno-thyroid muscle. 



Opposite this ridge-like tubercle, the body of the thyroid curves 

 abruptly backwards, and forms the conspicuous long posterior 

 cornu on each side. This is a stout rod, curved as it passes 

 backwards {i. e. posteriorly) with a rather strong convexity towards 

 the dorsal surface ; it is, of course, articulated at its hinder end 

 with the cricoid cartilage. 



Whereas the body of the thyroid is flat and band-like, the cornu, 

 though of the same character at its origin, .soon becomes a thick 

 subcylindrical rod. 



It is 4 inches long, measured from the anterior margin of the 

 body to the posterior end of the cornu. 



The body of the thyroid measures 5 inches from side to side ; 

 measured from the outer extremities its antero-posterior width 

 {i. e. length) is about one inch, though this becoDies greater 

 towards the middle ; the depth of the notch is | inch ; a line from 

 the bottom of the notch to the anterior margin, on the median 

 line, measures g inch. 



