394 ANATOMY OF VERTEBRATES. 



tongue arc due to muscular action. Any physiologist who has 

 felt the firm but regulated grasp of the tongue of the Giraffe, 

 when twined round the finger, must have recognised the difference 

 of the action from the fitful force arising from vascular or erectile 

 injection. The muscular fibres in the free and flexible part of the 

 tongue present an arrangement adequate to all its movements. 

 The stylo-c/lossi and inferior linyuales expand into a layer of 

 longitudinal fibres, about a line in thickness, covering the whole 

 of the inferior surface of the free portion of the tongue, and 

 becoming continuous at the sides, with a corresponding but 

 thicker stratum of longitudinal fibres on the upper surface of the 

 tongue ; these longitudinal muscles inclose a mass of fibres, 

 which run in the transverse direction. The action of the trans- 

 verse, combined with that of several short vertical, fibres near the 

 margins, and of those forming the thin circular stratum sur- 

 rounding the sti/lo-glossi at the middle part of the tongue, serves 

 to attenuate or diminish the transverse diameter of the tongue 

 and increase its length ; while thus rigidly extended the apex of 

 the tongue can be curved upward or downward by the superficial 

 longitudinal fibres, which are less intermingled with the trans- 



J3 > o 



verse fibres than in the tongues of most other Mammals : the 

 contraction of the longitudinal fibres taking place with the re- 

 laxation of the transverse ones produces the retraction of the 

 whole organ. The nerves of the tongue present the same dis- 

 position as those in ordinary Ruminants, but the ninth pair is 

 relatively larger than the branch from the fifth pair ; the nerve 

 which runs along the inner or under surface of the stylo-glossi 

 toward the free extremity of the tongue is remarkable for its 

 beautifully wavy course, by which it is accommodated to the 

 variations which occur in the length of the organ in the living 

 animal. 



The back of the mouth appears to be as completely closed in 

 the Giraffe as in the Capybara ; but, instead of contracting, like 

 a funnel, to a small circular depression, it terminates by a 

 transverse slit, through which projects the broad upper margin of 

 the epiglottis, which is folded upon itself. The faucial membrane 

 is coarsely corrugated. 1 The velum palati descends to the inter- 

 space between the epiglottis and the large arytenoid cartilages ; 

 and there is an uvular process from the middle of the inferior 

 margin. The tonsils are well- developed glands of a flattened 

 oval form, having each a short duct communicating by one wide 

 opening with the fauces. 



1 xcvn'. pi. xlii, fig. 3. 



