of the Tongue of the Chameleon. 1*67 



8th, The internal cerato-nuurillary is long and slender (Fig. 1, 2, 6, h), and si- 

 tuated deep in the mucous membrane of the mouth. It arises from the ante- 

 rior part of the side of the lower jaw, and passuig thence backwards on the 

 upper surface of the style and muscles, ends in a tendon, which, after uniting 

 with its feUow of the other side, about two lines before the articulation of the 

 cornu with the body of the os hyoides (Fig. 1. h), becomes broad, and is in- 

 serted into the roots of the posterior cornua. The last four muscles, by con- 

 tracting, will draw forwards the os hyoides, and protrude the end of its style 

 a short distance out of the mouth. 



9th, The hyo-glossus (Fig. 4, 6. iiii) arises from the outer extremity of the 

 posterior cornu of the os hyoides. At first it accompanies the cornu inwards 

 to near the body, then leaves it, winds round the cartilaginous pully on the 

 anterior cornu, runs forwards along the sides of the style and erectile portion 

 of the tongue, and is inserted into the anterior prehensile portion. This mus- 

 cle admits of remarkable elongation, as its extremities, which are not more 

 than an inch apart while the tongue rests in the mouth, become separated du- 

 ring its complete protrusion to a distance of five or six inches. It can only 

 exert an action on the prehensile portion of the organ, which it retracts into 

 the mouth after having been protruded in the search for insects, and which it 

 may settle and keep steady when so retracted. 



The moveable portion of the tongue consists of two parts, which are dis- 

 tinct from each other both in their structure and functions. One of them I 

 propose to name prehensile, the other erectile. 



The first, or preliensile portion, is anterior (Figs. 2, 3, 2, T, E. ) It is some- 

 what cylindrical, about an inch and a quarter in length, and an inch in cir- 

 cumference. Its bulk undergoes no change during the elongation or retrac- 

 tion of the tongue, in consequence of its being surrounded by a dense fibrous 

 sheath, which prevents any such alteration. Its anterior extremity is hol- 

 lowed into a pouch lined with mucous membrane (Figs. 3, 4, 5), which is 

 rugose, and smeared with a viscid adhesive matter for entangling the insects 

 it strikes against. During the projection of the tongue the lips of this pouch 

 are everted so as to expand considerably its surface. Its posterior extremity 

 is smaller than the anterior, and continuous with the erectile portion. The 

 anterior half of its superior surface is occupied by an oblong glandular body 

 (G), from which perhaps is secreted the glutinous coating of its extremity. 

 The openings of this gland are on its lower surface, next the pouch, on which 

 it rests. (Fig. 5, m.) On the posterior half of this surface the ramifications 

 of large blood-vessels are observable. Along its sides, posteriorly, the inser- 

 tions of the hyo-glossi muscle present themselves. Its inferior surface i.s 

 smooth and rounded. A tube (Fig. 5, p,p.) about the thickness of a small 

 crow's quill runs through its centre. This tube is prolonged into it from tlie 

 erectile portion, and serves as a resting place for the style of the os hyoides, 

 which it surro\inds like a sheath, when the tongue is drawn into the mouth. 

 It is encircled by an annular muscle (Fig. 5, o, o), the fibres of whicli arc 

 very numerous and strong, and have but a loose connection with the tube. 

 This muscle may, by contracting round the tube when it rests on the style, 

 prevent its revolving on that bone, and thereby make steady the prehensile 

 j)ortion, and adapt it for the ordinary uses of tlie tongue in mastication. Two 



