Reptiledom

It is generally allowed that birds have risen out of reptiledom.

It is common enough practice for them to turn cannibals and eat their own offspring — rather despicable business, this eating of one's own children, but possibly considered good form in reptiledom.

For hibernation means more than taking a long sleep when it is very cold and the metaphorical wolf is at the door; it means a definite imperfection in the warm-bloodedness, and a peculiar lapse towards reptiledom, with very remarkable constitutional changes in heart and blood, in breathing and excretion.

Leaning against bookcases filled with medical works were huge test tubes of alcohol and formalin preserving the remains of many of the most dangerous characters of reptiledom.

In the absence of earlier eggs, it is hard for scientists to tell exactly when the amphibians crossed the threshold into reptiledom, for the earliest known reptiles are so amphibianlike that their assignment to one category or the other is largely a matter of opinion.