REPTILIA. 309 



Family XX. Chamceleonidei (Chamceleontes WIEGM.). Teeth 

 of jaws united to the margin; palatine teeth none. Tongue pro- 

 tractile to a great distance, fleshy, round, thick at the apex, 

 glutinous. Scales small, granular. Feet four, slender, pentadac- 

 tylous, with toes divided into two opposite fasciculi. Membrane of 

 tympanum concealed under skin. 



Chamcelean GRONOV., MERR., FITZ., WAGL., Chamceleo LAUR., 

 DUM., BIBR. Characters those of the family. (Teeth compressed, 

 anterior very small, posterior larger, tricuspidate. Occiput produced 

 into a kind of helmet. Outer toes of fore feet two, of hind feet 

 three. Femoral pores none. Two horizontal eyelids concrete to 

 form a single circular eyelid, furnished with a small aperture in 

 front of the large eye. Back compressed, keeled. Tail prehensile, 

 long.) 



The genus Chamceleon is clearly distinguished from all the other 

 Saurii, however Lyrioceplialus in some degree resembles it. Most 

 of the species belong to Africa, and especially to the island of 

 Madagascar; the common North- African species occurs also in 

 Spain, and was known to the ancients, who in regard to the changes 

 of colour of this animal, advanced the erroneous opinion that its 

 colour changes to that of the objects on which it is placed. Cha- 

 meleons are not more remarkable for this change of colour than 

 for the motion of their tongue as swift as an arrow 1 . By this the 

 sluggish animals capture the insects on which they feed; with the 

 mouth itself or with the feet they never seize their prey. 



1 According to HOUSTON, when this takes place there occurs at the same time 

 a swelling from congestion of the blood-vessels, a true erection. Essay on the structure 

 and mechanism of the tongue of the Chamcdeon, Transact, of the Roy. Irish. Acad. 

 Dublin, 1828 ; this opinion was, however, afterwards contested by RUSCONI (MUELLER'S 

 Archiv, 1844, s. 508 519). It is simply a muscular action ; the hyo'id bone is pro- 

 duced into a slender tapering style which penetrates the tongue and is surrounded by 

 a lax and mucous sheath. The m. m. geniohyoldeus and mylohyoldeus move this style 

 forwards upon the horns of the hyo'id bone, whilst, in the substance of the tongue 

 itself, there are also curved and decussating muscular fibres which radiate from the 

 circumference to the center and press upon the organ in such a way as to cause it to 

 glide along the lingual style of the hyo'id bone. These fibres form what BRUECKE calls 

 the m. accelerator lingucs. See his remarks on the tongue of the Chameleon in 

 Sitzunysberichte der math, naturw. Classe der Kaiserl. Acad. der Wissensch. vin. 1852, 

 s. 65 and foil. Similar independent observations were published at the same time by 

 J. ZAGLAS in J. GOODSIR'S Annals of Anat. and Physiol. Edinb. 1852, no. n., 

 pp. 138 153, PI. vi. See also a careful dissection and explanation of the movements 

 of the tongue of the Chameleon by SALTER in TODD'S Cyclop, of Anat. and Phy- 

 siol. iv. pp. 1147 1150. 



