REPTILIA. 



293 



has no occasion to move in search of insect 

 prey, but waits patiently until its victims 

 approach sufficiently near to be within reach 

 of its singularly constructed tongue ; which, 

 although ordinarily concealed within the 

 cavity of the mouth, is capable of being 

 elongated until it exceeds in length the whole 

 body of the animal. No sooner does a fly 

 approach within five or six inches of the 

 chameleon, than the tongue is slowly pro- 

 truded for the length of about an inch, so as 

 to expose its thick fleshy extremity, the end 

 of which is divided into two prominent lips, 

 and copiously lubricated with a thick viscid 

 secretion. The whole tongue is then launched 

 out with a rapidity that is perfectly amazing, 

 to the length of six or seven inches, and a fly 

 glued to its extremity is brought into the 

 creature's mouth so quick-Iy that the eye can 

 scarcely follow the movement. 



The following is Mr. Hunter's description of 

 the anatomy of the tongue of the chameleon. 

 " The tongue ef the chameleon consists of 

 four parts : first, a long basis ; second, a 

 pulpy or bulbous part, at the tip of the 

 tongue; third and fourth, elongating and 

 contracting parts, which run almost through 

 the whole length. 



" The basis, or bony apparatus of the tongue, 

 consists of an os hyoides and os linguae, 

 somewhat similar to that of a bird ; there- 

 fore there is nothing very, remarkable in their 

 construction. 



"The bulbous, or thick part at the end of 

 the true tongue, is that part which is to 

 manage the food when caught; it is the 

 operator within the mouth, of which it is the 

 pincher or catcher, from its being formed at 

 the end into two opposite points, similar to 

 the elephant's snout. This surface is ru- 

 gous, and covered with a gelatinous slime. 



" The basis and true tongue or tip are united 

 by an elongated and contracting medium, 

 which is very extensive. This length of 

 tongue, its extension, and contraction, are 

 very singular, and, if well understood, most 

 probably very curious. 



" The cause and mode of the contraction of 

 its length are not uncommon.. The elonga- 

 tion of the tongue in this animal is perhaps 

 like nothing that we are acquainted with in 

 an animal body. 



" The apparatus for the purpose is a small 

 rounded body which passes from the apex of 

 the os linguae (glosso-hyal) to the bulbous 

 parts, and then through the centre of the 

 bulb. The part between bone and bulb con- 

 sists of two different substances ; one a 

 whitish, substance, which is the firmest, and 

 appears to be capable of keeping its form: 

 the other is softer and more transparent. 

 That part which passes through the bulb 

 consists only of one substance,, and appears 

 to be a sheath for the reception of the os- 

 linguae 



" The first of these (i. e. the whitish firmer 

 substance) appears to be composed of rings, 

 or something similar, placed obliquely in con- 



trary directions, so as to appear to be two 

 spirals crossing one another. Whether the 

 other, or softer substance, has any direction 

 of fibres, I could not observe, but I suspect it 

 is muscular. If I am right in my conjecture, 

 and of its disposition, it will be no difficult 

 thing to show how it may be elongated ; for 

 if these rings are placed transversely, they may 

 be brought so near to one another as to 

 shorten the whole very considerably ; and if 

 they allow of being placed almost longitudi- 

 nally, they must of course lengthen it very 

 considerably ; and this position can be easily 

 produced by muscles, which I take the pulpy 

 substance to be, 



*' The contraction of the tongue is owing to 

 a degree of elasticity, but this appears to be 

 only in the cellular membrane, acting as an 

 assistant to the muscular. The muscular 

 contraction is owing to two muscles, one on 

 each side of the tongue : each arises from the 

 os hyoides, on the inside of the os linguae, 

 and passes along the side of the tongue to its 

 bulbous part ; but before it gets to the bul- 

 bous part, it spreads itself all round. 



"In the centre of each of these two muscles 

 passes a considerable nerve to the bulbous 

 part, and also two arteries. When the two 

 muscles act, they draw the tongue back upon 

 the os-linguae, which, as it were, passes 

 through the middle elongator, then through 

 the centre of the bulb, till the whole tongue is 

 retracted. Although this middle body is 

 drawn upon the os-linguae, yet it does not 

 appear to be hollow, like a pipe ; it rather 

 appears to be filled with a very ductile cellu- 

 lar membrane, as in every part of the elonga- 

 ting division of the tongue, in order to allow 

 of the great difference in the situation of parts 

 with respect to one another." 



In the Crocodiles, the structure of the 

 tongue is equally, remarkable, but of a very dif- 

 ferent character^ In these reptiles the tongue 

 has no projecting or moveable extremity, 

 being attached by, its whole circumference to 

 the rami of the lower jaw, insomuch that it 

 was described by Aristotle as being entirely 

 deficient. Its whole surface is covered over 

 with a thick coriaceous skin, upon which may 

 be seen the openings of innumerable glandular 

 follicles situated beneath it. At the posterior 

 part of the organ, close to the opening of the 

 fauces, the broad anterior part of the hyoid 

 cartilage supports a broad fold of the skin 

 that covers the tongue, which can be applied 

 like a valve against a corresponding fold of 

 the palatal membrane that descends from the 

 roof the mouth, so that the two, when ap- 

 proximated,.form a valve that completely closes 

 the communication between the mouth and 

 the posterior fauces. By this arrangement 

 the crocodile is enabled to keep its mouth 

 open under water without danger of suffo- 

 cation from that fluid getting into its trachea, 

 whilst by means of its long tubular nostrils, 

 which open at the very apex of its snout, and 

 are continued^backwards to behind the valvular 

 apparatus above described, it is enabled to 

 . u 3 



