INTRODUCTION TO THE CLASS OF REPTILES 
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south of that zone, reptilian life still is abun- 
dantly represented, but chiefly by small species. 
The largest land-serpents are found in the low- 
lying, moist and hot forests of the equatorial 
regions; but crocodilians of the largest size are 
found several hundred miles from the equator, 
both north and south. The largest tortoises live 
directly on the equator. 
Poisonous Species, — Among our reptiles only 
one lizard and a few species of serpents are ven- 
omous, — an exceedingly small proportion of the 
whole number. Indeed, so few in number are 
the dangerous species of North America, it is 
an easy matter for any intelligent person to 
learn to recognize all of them at sight. In a few 
hours of diligent and conscientious study, aided 
by a text-book that has been properly designed, 
any clear-headed person over fourteen years of 
age can learn to determine almost at a glance 
whether any fully grown serpent of North Ameri- 
ca is poisonous or harmless. This is possible 
from the fact that more than half of the venom- 
ous species possess rattles, and those which have 
not are few in number. 
Useful Species. — Many reptiles are of de- 
cided value to mankind, by reason of the rats, 
mice and other destructive vermih which they 
destroy. Others diligently devour insects. Quite 
a number furnish useful food, and some yield 
skins and other commercial products of much 
value. 
Lack of General Knowledge Regarding 
Reptiles. — While birds have been well taken 
care of in books, museums, zoological gardens and 
lectures, and mammals are now coming in for a 
small proportion of the attention they deserve, 
the reptiles have been greatly neglected. Very 
few zoological institutions contain collections of 
reptiles worthy of the name, and the books on 
this Class are mostly to be written. As a result 
of this well-nigh universal lack of opportunity 
for study, the great majority of persons possess 
very little precise and clear information regard- 
ing these creatures. The following chapters are 
offered merely as a foundation on which to build 
an acquaintance with a world of living creatures 
concerning which we are assured that a large 
number of persons sincerely desire information. 
