700 REPTILIA—BOA CONSTRICTOR. 
into several brighter colors, pale yellow, or vivid crimson, which form spots 
of the size of half one’s finger; some of these descend from the spine half 
way down the back ; and others appear on the sides, arms, and tail. Some- 
times the animal becomes all over spotted with brown spots, of a greenish 
cast. When it is wrapped up in a white linen cloth for two or three 
minutes, the natural color becomes much lighter, but not quite white, as 
seme authors have pretended; however, it must not hence be concluded 
that the chameleon assumes the color of the objects which it approaches ; 
this is entirely an error, and probably has taken its rise from the continual 
changes it appears to undergo. 
When the chameleon changes place; and attempts to descend from an 
eminence, it moves with the utmost precaution, advancing one leg very 
deliberately before the other, still securing itself by holding whatever it can 
grasp by the tail. It seldom opens the mouth, except for fresh air; and, 
when that is supplied, discovers its satisfaction by its motions, and the fre- 
quent changes of its color. The tongue is sometimes darted out after its prey, 
which are flies; and this is as long as the whole body. The eyes are re- 
markably little, though they stand out of the head; but the most extraordi- 
nary part of their conformation is, that the animal often moves one eye, 
when the other is entirely at rest; nay, sometimes one eye will seem to look 
directly forward, while the other looks backward ; and one will look upwards, 
while the other regards the earth. 
ORDER: Lil. —OP RT DiA: 
THE ophidia, or serpents, have a heart with two auricles ; body much elon- 
gated, cylindrical, destitute of feet, generally covered with scales. 
THE BOA CONS TRL GOR. 
Tue ground color of the body of the great boa, which is the largest and 
Strongest of the serpent race, is yellowish gray, on which is distributed, 
along the back, a series of large, chain-like, reddish brown, and sometimes 
perfectly red variations, with other small and more irregular marks and 
spots. 
The great boa is frequeatly from twenty-five to thirty feet in length, and 
of a proportionate thickness. The rapacity of these creatures is often their 
own destruction; for whenever they seize and swallow their prey, they 
seem like surfeited gluttons, unwieldy, stupid, helpless, and sleepy. They 
at the same time seek for some retreat, where they may lurk for several 
1 The genus Boa has the anus with a hook on each side; hody compressed, thickest in 
tne middle; tail prehensile; scales small, at least upon the posterior part of the head. 
