162 Mr Houston o»i the Structure and Mechanism 



sufficient health'to lake food in their natural way, an opportu- 

 nity, such as rarely occurs, was afforded nie, both of observing 

 their tongues in the aci of elongation during life, and of making 

 a most satisfactory examination of their structure immediately 

 after death. I therefore entertain a hope that the facts which 

 I have collected, under such favourable circumstances, may be 

 calculated to remove much of the obscurity in which the subject 

 has been hitherto involved. 



The animals were brought from Malaga in the month of Oc- 

 tober 1826. They corresponded in characters to the Lacerta 

 Chameleon of Linnasus. One measured twelve inches in length, 

 the tail included, the other ten. Both were females, and con- 

 tained numerous ova, which could be felt through the thin pa- 

 rietes of the abdomen. One of them while in my possession dis- 

 charged, apparently with much labour, two eggs which were of 

 an oval form, about the size of a wren's, and covered with thin 

 Yellowish coriaceous shells. 



The external surface of their skin was thickly set with soft 

 tubercles, like the heads of small nails, some of a whitish, 

 others of a bright yellow colour : the white tubercles were most 

 numerous, and existed every where over the body ; the yellow 

 ones were so arranged as to form along each side of the back 

 two rows of lozenge-shaped spots, and round the legs and tail 

 annular l>ands. When examined in the morning, or during 

 sleep, the whole surface presented a greyish cast, with the excep- 

 tion of the yellow marks; but when the animal was excited in 

 any way, as by pricking, or transferring it from a cold to a 

 warm temperature, an evident change of colour took place, 

 sometimes all over the surface, sometimes only partially, ac- 

 cording as the excitement affected the entire or only a part of 

 its body. A brownish tinge gradually overspread it, engaging 

 equally the tubercles and the intermediate skin ; while the spots, 

 which were previously yellow, acquired a slight admixture of 

 trreen. The shades, however, were few, and confined to those 

 intermediate between a light grey and a deep brown, with a 

 little yellow or green interspersed through them, but never, that 

 I could observe, bore any relation to the colour of the surface 

 on which the animal happened to be placed. In dissecting the 

 akin after death, its exceeding thinness and vascularity attrac- 



