284 PROr. W. B. BENHAM ON THE [^Pf- 2, 



" process," and of a thiu lamelliform, antero-ventrally placed 

 " wing." (PL XXVII. fig. 15.) 



Of these, the body and the " wing " are visible from without, 

 after removal of the muscles, while the posterior " process " can 

 only be seen by removal of the wall of the larynx. 



The '•' body," or processus museularis, of the arytenoid is some- 

 what conical, with an obtusely rounded apex directed forwards 

 and outwards (Pi. XXV. fig. 2) ; the base — measuring l^j inches — 

 is narrow and elongated transversely ; it articulates with the cricoid 

 in a typical fashion at the antero-lateral dorsal margin of the 

 latter ; its apex serves for the insertion of the erico-arytenoid 

 muscles. 



The anterior " wing-like " process ( = supra-arytenoid of 

 Thompson) rises from the body by a comparatively thick basal 

 region, but this soon becomes a thin plate, which is somewhat 

 ci^escentic in form — the form is, after all, best appreciated by a 

 study of the figures. One horn of the crescent is directed forwards 

 and dorsally, and the right and left " u'ings " approach one another 

 at their extremities, supporting the " arytenoid bodies." 



The posterior half of the crescent is continuous with the 

 posterior process of the arytenoid : the convex margin of the 

 " vv'ing " is directed inw^ards, towards the cavity of the larynx ; its 

 extreme edge is reflected outwards, and the whole of the lower 

 half of the wing is set at an angle with the plane of the posterior 

 process, so that a " fossa '" is enclosed by them. 



In this fossa, to the external concave face of the arytenoid 

 wing, are inserted the upper portions of the aryteno-epiglottidean 

 mviscles. 



The third part of the arytenoid, the posterior " processus 

 vocalis," arises from the body by a broad stout base ; its long axis 

 is directed backv\ards, parallel to its fellow, close to the dorsal 

 wall of the larynx. In addition to serving for the insertion of 

 the loAver aryteno-epiglottidean muscles and the thyro-arytenoids, 

 these two processes form the margins of the true entrance into 

 the laryngeal sac. 



The total length of the arytenoid is 4 inches, measured in a 

 straight line from the anterior end of the " wing " to the posterior 

 tip of the " process." 



In the G-reenland Eight Whale the two processus vocales of the 

 arytenoid cartilages are continuous at their distal ends, forming a 

 posterior support for the laryngeal opening; this is not the case 

 in the young Eorqual, though the ends were connected by dense 

 connective tissue, and very probably this became replaced by 

 cartilage in older animals. 



The ejngloUid cartilage is embedded in the aryteno-epiglottid 

 and other muscles, so that only a small piece of 'it comes to the 

 surface. On dissection, however, the cartilage is found to have the 

 usual form (PI. XXVI. figs. 11, 12), resembling a shoe-horn; 

 it consists of an upper thin plate (a) with a wide shallow groove, 

 and a lou er thicker moiety (&) which is connected by fibrous tissue 



