REPTILIA. yal 
yellow vipers, neither is poisonous, nor even in the slightest degree noxious, 
although of quite terrific appearance and demeanor when enraged. 
An exceedingly interesting illustration of the special provision which nature 
sometimes makes for particular cascs is seen in the African genus Deirodon. 
To this has been imputed the instinct of living almost entirely on the eggs of 
birds, and its whole organization fits it expressly for this end. ‘The mouth is 
entirely without teeth, at least in the adult, so that nothing interferes to prevent 
the ready entrance of an egg into the open jaw, and there is no liability of its 
losing any of the contents by a premature breakage. The inferior spinous 
processes of the seven or eight inferior cervical vertebr project with the 
cesophagus, where they are capped by a layer of lard cement and made to 
resemble long sharp teeth. The descending eggs press against these teeth and 
are sawed open longitudinally, and then, crushed by the contractions of the 
gullet, are carried into the stomach, where the shell is probably dissolved by 
the gastric juice and digested with the contents. 
OrpeER 3. SauvurRIia. 
The third order of Reptiles, the Sauria or Lizards, embraces species of 
very diversified character, especially when we take into consideration certain 
fossil forms. Their size, too, varies from that of a few inches to 30 feet, as 
in some recent crocodiles. This magnitude, however, is far exceeded by 
certain extinct species. The body is «generally cylindrical, sometimes 
slightly depressed, elongated, and with a skin provided with scales ( photides), 
granulations, or bony plates. The photides they share with the Ophidia, 
and the two orders are thus distinguishable from Batrachia, only a single 
family of which, the Ceciliad@, has minute cycloidal, fish-lke scales, nearly 
concealed in the folds of the skin. By the four feet they are distinguishable 
from serpents, although, in a few instances, these members are partly or 
entirely wanting externally. The feet, when present, are usually provided 
with true claws, supported on the terminal phalanges. The tail is developed 
toa greater or less extent, while the cloaca presents itself externally as a 
transverse slit. The almost universal presence of an external meatus 
auditorius, or at least of a tympanum (excepting in Acontias, yphline, and 
a few others), distinguishes the Sauria from the Ophidia; as also the presence 
of a sternum, connected with the vertebral column by movable ribs, and 
the greater immobility of the bones of the head. The rami of the lower 
jaw are firmly united together, and the entire skull is compact. Few Sauria 
are without movable eyelids, although these are occasionally very rudimentary. 
The teeth are variously disposed, as will be seen when we come to consider the 
different families. Many species are only known to us in a fossil state, these 
generally of great size. 
Fam. 1. Scincide. This family, standing at the foot of the great order 
of Saurians, is characterized, in the first place, by the possession of large 
plates on the top of the head, which are in contact along the edges ; and by 
their angular and regular shapes, closely resemble the homologous plates of 
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