598 ANATOMY OF VERTEBRATES. 



defined, the upper ones are broad; above their epiglottidean at- 

 tachments there is a widish sac : the intercordal ventricles are 

 moderate. 



Among Platyrrhine Quadrumana the larynx of Hapale, Calli- 

 thrix, and Cebus retains the moderate proportions of that in Lemu- 

 ridce : it is relatively larger in the Spider-monkeys (Ateles) and 

 attains, with the hyoid, an enormous size in the Howlers (Mycetes, 

 fig. 471). In most the upper border of the thyroid is emarginate : 

 but Ateles arachnoides and Hapale rosalia are exceptions ; instead 

 of the notch there is a median process, and a small sacculus pro- 

 jects from the crico-thyroid interspace : the santorinian cartilages 

 are confluent at their apices, and distinct from the cuneiform 

 cartilages, in Cebus and Hapale ; but both are fibrous rather 

 than gristly : they appear as processes of the upper vocal cords. 

 These are attached to the thyroid like the lower cords, which 

 there rather overlap them : the ventricles are moderate : the rima 

 glottidis is ordinarily wide and almost perpendicular : the basi- 

 hyal is not excavated. In Ateles the basihyal is quadrangular 

 and excavated: the santorinian and cuneiform bodies coalesce 

 with each other and with the epiglottis, of which they seem to be 

 processes. In the Howler {Mycetes) the cricoid, though small in 

 proportion to the rest of the larynx, is larger than in other 

 Platyrrhines and remarkably thick and powerful, especially 

 behind : it is ossified, and impressed on each side, near the lower 

 posterior angle, by an articular cavity for the short obtuse lower 

 horn of the thyroid. This cartilage shows a still larger relative 

 size, which is thrice that of the human thyroid : it makes a 

 strong anterior prominence, bulging out there to lodge a pair of 

 sacculi continued from the fore part of the long intercordal cleft 

 or ventricle. The arytenoids are small, with their uncinate apices 

 continued into a large fibro-cartilaginous mass, representing vastly 

 developed and confluent santorinian and cuneiform cartilages, 

 connecting the arytenoids with the long sigmoid epiglottis, and 

 including the scarcely distinguishable upper vocal cords. The 

 lower ones are broad, but well defined. From the fore part of the 

 intercordal space the pair of sacculi are developed which line or 

 occupy the thyroid bulla. The epiglottis is more than 4 inches in 

 length and 2 inches in breadth, with the sides bent down so as to 

 form a kind of arch above the glottis. The ' rima ' so covered 

 consists of an anterior semilunar portion, from which a chink 

 extends backward, dilating into an oval aperture. Between the 

 glottis and the arytenoid cartilages are the orifices of a pair of 

 pouches, continued rather from the pharyngeal than the laryngeal 



