THE ANATO^rV OF THE CHIMPANZEE. 45 



The Larynx. 



The general shape and structure are well known. Seen from above and behind (the 

 posterior wall of the cricoid having been divided in the median line), the larvnx is pro- 

 portionately narrower than in man. The epiglottis is smaller and far less prominent. 

 The fossae at the back of the tongue and tlie glosso-epiglottidean folds are much less 

 marked. Another and more important consequence is, that the aryteno-epiglottidean 

 folds bounding the entrance to the larynx proper do not project nearly so freely as in 

 man. The notch behind is narrower and deeper. The prominence on either side formed 

 by the cartilage of Santorini is further forward, taking the place occupied by the 

 cartilage of Wrisberg, which in this animal is wanting. 



The hyoid apparatus consists, as usual in apes, only of the basi-hyal and of two 

 thyro-hyals. The body of the bone is short and strongly cru'ved upward as well as 

 forward. Its breadth measured in a straight line from side to side is 2.4 cm. The 

 thyro-hyals, which are connected by joints, measure, the right 4.2 cm., and the left 

 3.8 cm. 



The two halves of the thyroid can be separated or approximated with such ease that 

 a want of union was suspected, but a cross-cut at the angle showed that the cartilage is 

 continuous. There is but a slight forward projection of the angle. The vertical length 

 of this between the two notches is 2.2 cm. Both cornua bend strongly inward, 

 especially the upper. Tiie oblique line ends below in a very prominent tubercle which 

 overhangs a deep fossa. The fibers of the crico-thyroid muscle are inserted into the 

 lower border of the cartilage, the tubercle, the fossa behind it, and the inferior cornu. 

 There is a suggestion of a separation into two layers described by Gratiolet and Alix 

 Tlie superior cornu is separated from tlie extremitj- of the great horn of the hyoid In' a 

 nodule (cartilago triticea) which touches both. The flexibility of the superior cornu is 

 very striking. 



The cricoid cartilage has not been uncovered, for it was thought best not to dissect 

 the larynx. Its height in front is 7 mm. and behind 2.1 cm. 



The arytenoids, for the same reason, are not accessible. 



The true vocal cord is 2.-3 cm. in length. Its delicacy has been described by others. 

 It seems nothing more than a very thin fold of mucous membrane. The greatest 

 distance between the true and false cords across the middle of the entrance of the 

 ventricle is 5 mm. 



The ventricles and the roaring sac. Each ventricle is prolonged upward behind 

 the h3n)id to the side of the epiglottis for more than 1 cm. from the superior curd. The 



