146 REPTILES 



serpents ; their dentition being apparently similar to that of the 

 front-fanged colubrine snakes. The anterior teeth are curved 

 and fang-like, and provided with grooves for the transmission of 

 poison secreted by the salivary glands ; and, as in most serpents, 

 there are also smaller solid teeth on the palate. As these 

 reputedly poisonous lizards are certainly not the ancestors of 

 snakes, it is evident that their poison-apparatus has been de- 

 veloped independently of that of the latter. The reader will 

 notice that in the preceding sentence the expression " reputedly 

 poisonous" has been employed. Till a short time ago no doubt 

 was entertained that these lizards were venomous, and reports 

 are extant of the serious effects of their bite on guinea-pigs. 

 Recently, however, an American zoologist has thrown doubt on 

 their poisonous properties ; although still later the poisonous 

 character of the saliva has been reaffirmed in France. 



Venom and venom-fangs are, as already mentioned, con- 

 nected both with the function of procuring food and with attack 

 and defence, although in most cases mainly with the former ; 

 and it would accordingly be appropriate to follow with other de- 

 fensive and offensive adaptations. Before doing so, however, it 

 is convenient to refer to one remarkable adaptation connected 

 with the procuring of food, namely the tongue of the chamseleon. 

 This organ attains a remarkable development, being capable of 

 protrusion to a distance of seven or eight inches from the mouth. 

 The true tongue is a club-shaped organ, covered with a sticky 

 secretion which retains the victim at which it is projected with 

 unerring aim. This base, or root, on the other hand, is very 

 narrow, and composed of highly elastic tissue. It is supported 

 upon a special process of the hyoid bone, over which it is with- 

 drawn in telescope-fashion ; the whole apparatus, while in the 

 contracted state, being comparable to a spring-coil. From the 

 base a pair of elastic blood-vessels and a mass of special elastic 

 tissue extend into the true fleshy tongue. Congestion of the 

 blood-vessels, combined with the action of some of the hyoid 

 muscles, serves to release the spring-like arrangement, with the 

 result that when this occurs (at the will of the creature, or as 

 a kind of reflex action induced by the proximity of food, as 

 the case may be), the thick and club-shaped tongue is suddenly 

 and forcibly shot from the mouth to its full extent. The sticky 

 termination of the club at the same time opens out into an 



