THE ANATOMY OF THE INDIAN ELEPHANT. 



53 



grasped by the lips so as effectually to stop the entrance of air into 



the cavity, and thus at once, if I may so express it, the pump-action 



of the trunk is completely paralysed. 



We find, therefore, that it is to some 



modification of the throat that we must 



look for an explanation of the function 



in question, and this we find to be as 



follows : — The superior aperture of the 



pharynx (fig. 1, A) is extremely nar- 

 row, so much so as to admit with 



difficulty of the passage of the closed 



fist. Immediately posterior to this 



narrow aperture the pharynx dilates 



into a pouch of large size (fig. 2, E), 



capable of containing a considerable 



quantity of fluid. This pouch is pro- 

 longed forward beneath the root of 

 the tongue, and is bounded in the 

 follo^ving manner. The floor extends 

 from the epiglottis as far forward as 

 the root of the tongue, being formed 

 from behind forward by the thyroid 

 cartilage, thyro-hyoid membrane, and 

 hyoid bone. Its lateral walls are com- 

 pleted by the sides of the pharynx 

 (that is, by the superior constrictor 

 muscles — fig. 2, F), in addition to the 

 stylo- (G), and hyo-giossi (H) muscles. 

 The root of the tongue forms the anterior 

 boundary, whilst the posterior wall is 

 completed by depression of the soft 

 palate, or when the latter is elevated, 

 the pouch then communicates freely 

 with the oesophagus. In connection 

 with this pouch is to be observed 

 the very peculiar form of the hyoid 

 bone, which, being deeply concave 

 on its upper surface, forms as it were the greater part of the floor of 

 this pouch. Between the pouch and the concavity of the hyoid bone, 

 moreover, there is placed a large quantity of loose and distensible con- 

 nective tissue, which permits of the expansion of the pouch. The 

 size of the latter is, moreover, liable to alteration by the actions of 



, several muscles. These are more especially the hyo-glossi muscles, 

 and two little additional muscles (fig. 2, K), the homologies of which I 

 have not yet been able to determine, which, springing from the middle 

 line of the hyoid bone, in front of the pouch, pass up, one on either 

 side of the middle line, and blend mth the other muscles forming the 

 root of the tongue. By the action of these muscles the pouch may be 

 diminished in depth ; but in consequence of the narrow interval exist- 

 ing between the hyoid cornua, the length of the pouch from before 



Fi 



1. — A, superior aperture of 

 jiharynx. B, root of tongue. 

 C, soft palate with larynx pro- 

 jecting tlirougli the centre. D, 

 pharynx. 



