1148 



TONGUE. 



mouth, it is seen to be a whitish, fleshy, ru- 

 ratus and muscles, and from the description of 

 the two deduce the most probable explanation 

 of the movements. 



When a portion of the integument and 

 lower jaw on one side is removed, so as to 

 expose the tongue when retracted within the 



gous mass, about an inch and a half long, fill- 

 ing the buccal cavity, so as to depress the 

 floor of the mouth and throat, in shape some- 

 thing of a cone with the base in front : the 

 posterior half, or smaller part, is seen to be 

 thrown into deep and numerous transverse 

 rugae (fig. 761. A, b, and C.) which extend 



Fig. 7G1. 



Tongue of the Chameleon. 

 A, retracted. B, elongated. C, seen from beneath, in situ, by incision and separation of the integument. 



quite up to the hyoid bone, and give to this 

 part the appearance of an earth-worm, a simile 

 suggested by Belorr. When the tongue is 

 drawn out it is seen to be capable of great 

 extension (B), the extension taking place 

 in the posterior or rugose portion, and being 

 effected by the obliteration of the transverse 

 rugae, which one by one are smoothed or 

 flattened out as the extension is continued, 

 so that when it is stretched as far as it will go 

 by moderate traction, the tongue, instead of 

 being an inch and a half long, of which only half 

 is occupied by the extensible portion, is five 

 inches long, the extensible part occupying 

 about six-sevenths of the entire extent, and 

 being much attenuated (B, 6), while the an- 

 terior portion retains its original size and 

 shape (a). The tongue is thus seen to be 

 composed of two parts, a club-shaped ex- 

 tremity and a highly extensible medium of 

 connection between this extremity and the 

 hyoid bone : these two parts I shall now 

 describe. 



The anterior club-shaped extremity is about 

 three quarters of an inch long, and three lines 

 in diameter, and in shape reminds one of the 

 corolla of a labiate flower ; in fact it is bilabi- 

 ate : it has a sort of dome above (a), termi- 

 nated in front by an upper lip (c), which is 

 opposed by a more projecting lower lip (d), 

 and between them is situated a funnel-shaped 

 mouth, which, when closed, as in A, forms a 

 horizontal cleft, but is capable of being opened 

 as shown in B, (and to an extent greater than 

 that represented in the figure,) and closed on 



any object at the will of the animal, so as to 

 assist in the prehension of food. These lips 

 are furnished with a sort of orbicularis, and, 

 no doubt, too, with muscles that shall raise 

 the upper and depress the lower ; but I have 

 been unable to detect any fibres going in such 

 a direction as to produce these movements. 

 This part, as well as the whole of the tongue, 

 is invested with the mucous membrane of the 

 mouth, and the upper surface of the dome and 

 lower lip, are covered with minute papilla?, 

 invested with a fine epithelium, and disposed, 

 in the former situation, in rows, indicated by 

 the lines (A, ). The part which covers in 

 the infundibular cavity, and which, after the 

 analogous part in a labiate flower, I have called 

 the dome, Bibron has not ill compared to a 

 tongue reversed. 



The second portion consists essentially of 

 a membranous tube, threaded, as it were, by 

 the long cartilaginous stilet, or tongue bone, 

 of the hyoid apparatus (the glosso-hyal). This 

 cartilaginous stilet, which has been errone- 

 ously described as bony, is about an inch and 

 a half long, and consequently passes through 

 the entire length of the tongue when re- 

 tracted, its anterior extremity being received 

 into the lower lip of the club-shaped portion : 

 it threads the tongue much in the same way 

 as a bodkin threads a bag when furnishing it 

 with a running string, and it is by the pucker- 

 ing of the membranous portion upon this 

 basis that the transverse rugae are formed. 

 The membranous tube itself (which has been 

 compared to a pipe, a piece of intestine, a 



