XII 



ANATOMICAL STRUCTURE 



569 



granules. Tiie eyes are very remarkaMe. The eyehalls tliein- 



selves are large, but the eyelids are united into one foM with 



a small central opening. However, when the Chameleon is asleep 



the margins of this opening sometimes become iiuir*' slit like. 



The right and left eye can be, and are incessantly, moved 



separately from each 



other, and the creature 



squints terribly. Each 



eveball, together with 



the ]iiii-h()le eyelid, is 



rolled up and down, 



backwards and forwards, 



independently of the 



other eye. This is a 



unitjue feature, but it 



also occurs in people 



who squint badly. The 



question " What, and 



how, do these creatures 



see ? " is therefore (piite 



idle, especially since in 



reptiles binocular vision 



does not exist at all and, 



consetpiently, cannot be 



PtLT, 



disturbed by squinting. 



The tongue has 

 attained an extraordin- 

 ary development. The 



tongue proper (Fig. 152) f^,. 149. _a, Dorsal, B, ventral, and C, lateral view 



is club-shaped and is oi the sknW oi Chamaeleon vulgaris, x 1. Cond, 



, . , ' . , occipital condyle ; £/^ ectoi)terygoid ; y!^(7, jugal ; 



covered with a sticky lac, lacrymal ; I'al, jialatiue ; I'ar, parietal ; Prf, 



secretion. The base or prefrontal ; Pt.f, postfrontal ; I'tg, i)terygoid ; 



. . Q, quadrate ; Sq, squamosal ; Vo, vomer. 



root 01 the tongue is very 



narrow, composed of extremely elastic til)res, and is supp(jrLi'd by 

 a much-elongated copular piece of the hyoid. The elastic part 

 of the tongue is, so to speak, telescoped over the style-shaped 

 copula, and the whole apparatus is kept in a contracted state like 

 a spring in a tube. 



A i)air of wide, very elastic blood-vessels and special elastic 

 bands extend from the base into tlie thick end of the tongue. 



