TONGUE. 



1H7 



umler the flattened cartilaginous plate of the 

 body of the hyoicl bone, over the anterior bor- 

 der of which they are reflected as over a pul- 

 ley, where, coming in contact with the under 

 surface of the last-mentioned muscles, they 

 curve backwards, radiate in a fan-like manner, 

 and form the under of the two muscular layers. 

 This is the position in a state of rest, the hyo- 

 glossus lying under the genioglossus, and the 

 extremity of the tongue pointing down the 

 throat in contact with the fauces, and forming 

 a plug with which to close the posterior nares, 

 and prevent the regress of air every time it is 

 swallowed. But when the animal would seize 

 its prey, the position of the tongue is sud- 

 denly reversed ; the genioglossus contracts, 

 and moving on its genial attachment as on a 

 centre, the tongue is thrown forwards, the ge- 

 nioglossus now being below, the hyoglossus 

 above. The apex of the tongue having come 

 in contact with the prey to be seized, and se- 

 cured it by its viscid secretion, the organ is 

 instantly retracted and restored to its original 

 position by the contraction of the hyoglossus. 

 In many of the batrachians (as in the Triton) 

 the tongue is fixed in its entire extent, and is 

 of very various shapes, oblong, rhomboidal, 

 heart-shaped, &c., affording generic and spe- 

 cific distinctions, of which zoologists have 

 availed themselves in classification. The 

 tongues of Batrachia are invariably soft, and, 

 in some of them, as the frog, covered with 

 well-developed papilla?, containing all the es- 

 sential elements of organs of taste and touch ; 

 that they are the seat of an acute sense of 

 taste is, however, highly improbable, not from 

 any thing in their structure, but from the fact 

 that these animals swallow their prey whole, 

 without any subdivision, frequently alive, bolt- 

 ing it as soon as seized. 



b. Ophidia. In the ophidians the tongue is 

 very much elongated, straight, flat or cylin- 

 drical, fleshy, highly protractile, and deeply 

 cleft at the apex into two tapering points 

 which are in a state of constant vibration when 

 the tongue is protruded. These points are 

 the extremities of two muscular cylinders, 

 which form the substance of the tongue, and 

 by their close apposition constitute that part 

 of it that seems to be undivided : they may be 

 traced a long way down in front of the tra- 

 chea. When the mouth is opened the tongue 

 very frequently cannot be seen, from its being 

 drawn within a sheath which contains it, the 

 orifice of which is placed in front of the aper- 

 ture of the glottis. From this sheath, and 

 from the mouth, it is being constantly pro- 

 jected, with a sort of vibratile darting move- 

 ment, and, from a deficiency in the plates at 

 the symphysis of the jaws, it can be protruded 

 from the mouth without the jaws being sepa- 

 rated : the character of this movement, and 

 the pointed slender shape of the tongue, have 

 given rise to the vulgar belief that it is the 

 animal's weapon of offence, a sort of dart con- 

 taining the poison that it instils into the 

 wounds it inflicts. From the nature of the 

 food of this order, from the disposition of the 

 parts of the mouth, and from the short so- 



journ that the food makes in it, the perception 

 of savours is probably very slight. 



c. Chelonia. In Chelonia the tongue is not 

 elongable, and its muscular structure is very 

 simple, consisting only of two pair of muscles, 

 the genioglossus and hyoglossus. In the tur- 

 tles the surface is smooth ; in most of the 

 tortoises it is clothed with very large and well- 

 developed papillae, long, soft, and flexible, 

 arranged with great regularity in a close pile : 

 the structure of these papillae, together with 

 the masticatory apparatus possessed by these 

 animals, would imply their possession of a true 

 sense of taste. 



d. Sauria. Among the saurians we find in 

 the Crocodile a fixed tongue projecting so 

 little from the floor of the mouth, that Aris- 

 totle, as has been stated, described it as want- 

 ing; it is covered with a coriaceous integu- 

 ment, and is remarkable chiefly for a valve-like 

 process at its base, formed by a reduplication 

 of the integument over the vertical ridge of 

 the body of the hyoid bone, which, at the will 

 of the animal, is capable of being applied to a 

 similar one descending from the palate, and 

 shutting off the mouth from the posterior nares 

 and larynx, so that the animal can breathe 

 when its mouth is under the water or engaged 

 with its prey, and its nostrils only above the 

 surface. In the Lizard we find a tongue, in 

 shape very much like that of the Ophidians. 



In the Chameleon we find an apparatus which, 

 for its remarkable structure and powers, has 

 always excited the attention and curiosity of 

 zootomists : Perrault, Hunter, Cuvier, Vallis- 

 nieri, Vrolick, Houston, Milne Edwards, 

 Spittal, Duvernoy, have all given their con- 

 tributions to the subject ; the connection of 

 the mechanism with the resulting phenomena, 

 as given by these authors, has been very di- 

 verse, and all, in the opinion of bibron, un- 

 satisfactory. " It is easy," says this author*, 

 " to conceive and explain a part of these 

 movements, by the structure of this tongue in 

 the chameleons, because the hyoid bone and 

 the muscles have been perfectly described, 

 and because it is easy to isolate them by dis- 

 section ; yet, by the very aid of this anatomy 

 we perceive that the movements which this 

 mechanism should effect would not suffice for 

 the production of such an excessive elongation, 

 that the animal, without using any violent exer- 

 tion, can lance from its mouth, by a sort of ex- 

 puition, a fleshy pipe of a length nearly equal to 

 that of its whole trunk, and that it can retract it 

 again within its throat with the same swiftness, 

 and without one's perceiving any apparent 

 movement in the rest of its body." The dif- 

 ficulty that Bibron felt was that of accounting 

 for the very great intrinsic elongation of the 

 tongue, and it appears to me to be a difficulty 

 that exists ; various authors account for it 

 variously; in my own dissections I have not 

 met clear evidence of anything that satisfac- 

 torily explains it to me. I shall first describe 

 the tongue itself, and then the hyoidean appa- 



* Erpetologie Gi'nerale, ou Histoire Naturelle 

 complete des Keptiles, Paris, 1830, t. iii. p. 174. 



