4 
REPTILES. 
Excepting some of the tortoise tribe, the Reptiles are carnivorous beings, and many of 
them, such as the crocodiles and alligators, are among the most terrible of rapacious creatures. 
In this class of animals we find the first examples of structures which transmute Nature’s 
harmless gifts into poison, a capacity which is very common in the later orders, such as the 
spiders and insects, and is developed to a terrible extent in some of the very lowest beings that 
possess animal life, rendering them most formidable even to man. 
The skeleton of a true Reptile, from which class the BotracMans , i. e. the frogs, salaman- 
ders, and their kin are excluded, for reasons which will presently be given, is composed of 
well-ossified bones, and is peculiarly valuable to the physiologist. It is well known to all who 
have studied the rudiments of anatomy, that each bone is formed from several centres, so 
to speak, consisting of mere cartilaginous substance at its earliest formation* and becoming 
gradually ossified from several spots. 
In the young of the higher animals these centres are only seen during their very earliest 
stages, and are by degrees so fused together that all trace of them is obliterated. But in the 
Reptiles it is found that many of the bones either remain in their separate parts, or leave 
so distinct a mark at the place where they unite, that their shape and dimensions are clearly 
shown. In the head of the adult crocodile, for example, the frontal bone is composed of five 
distinct pieces, the temporal of at least five pieces, and each side of the lower jaw-bone is 
composed of either five or six portions united by sutures. 
With the exception of the tortoises, the Reptiles mostly possess a goodly array of teeth, 
set in the jaw or palate, and as a general fact, being sharp and more or less curved backward. 
Their bodies are covered with various modifications of the structure termed the dermal, i. e. 
skin skeleton, and are furnished with scales and plates of different forms. In some cases the 
scales lie overlapping each other like those of the fish, in others they are modified into knobby 
plates, and in some, of which the tortoises afford well-known examples, they form large flat 
plates on the back and breast, and scales upon the feet and legs. 
The young of Reptiles are produced from eggs, mostly being hatched after they have been 
laid, but in some cases the young escape from the eggs before they make their appearance in 
the world. As a general fact, however, the eggs of Reptiles are placed in some convenient 
spot, where they are hatched by the heat of the sun. Some species are very jealous about 
their eggs, keeping a strict watch over them, and several of the larger serpents have a curious 
fashion of laying the eggs in a heap, and then coiling themselves around them in a great hollow 
cone. The size of the eggs is extremely variable, for, although as a general fact those of the 
smaller Reptiles are large in proportion to the dimensions of the parent, those of the crocodiles 
and alligators are wonderfully small, not larger than those of our domestic geese, and in many 
cases much smaller. They are usually of a dull white color, and in some instances are without 
a brittle shell, their covering being of a tough leathery consistence. 
In form, and often in color, the Reptiles exhibit an inexhaustible variety, and even each 
order displays a diversity of outward aspect unexampled in the two previous classes of 
Mammals and Birds. Strange, grotesque, and oftentimes most repulsive in appearance, 
though sometimes adorned ’with the brightest tints, the Reptiles excite an instinctive repug- 
nance in the human breast ; and whether it be a lizard, a snake, or a tortoise, the sudden and 
unsuspected contact of one of these beings will cause even the most habituated to recoil from 
its cold touch. This antipathy may, perhaps, have some connection with the instinctive asso- 
ciation of cold with death ; but whatever may be the cause, the feeling is deep and universal. 
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