136 THE STORY OF KEPTILE LIFE. 



instances where incubation of the eggs is sup- 

 posed to obtain, the real object is protection, 

 inasmuch as no appreciable increase in tempera- 

 ture was traceable in the case of the Indian 

 Python (Python molurus), which, during the 

 summer of 1881 remained for almost six weeks 

 coiled around her eggs, fifteen in number, in the 

 gardens of the Zoological Society of London. 



A receptacle for the eggs in the shape of a 

 nest appears never to be made, though the Nile 

 Monitor (Paramis nttoticus), is said to build itself 

 a nest among the bushes on the banks of streams, 

 especially those which dry up in summer. It 

 may happen, that further investigation will show 

 that this is used also for the eggs. 



That the progress of embryonic development 

 may be arrested and suspended for a relatively 

 long period of time is probably a fact not 

 generally known. Thus the eggs of one of the 

 northern Pond-tortoises (Emys orUcularis), laid 

 in the autumn, do not hatch out till the follow- 

 ing spring, withstanding the severe winters of 

 North Germany and Russia, though only a few 

 inches below the surface. Similarly, in the 

 "Tuatera" (Sphenodon punctatus), the eggs are 

 laid from November to January or February 

 the southern summer and by August contain 

 nearly ripe embryos. These, however, do not 

 hatch out till the following February, or till 

 the embryos are some thirteen months old. 

 During a large part of this time they seem to 

 undergo a sort of summer sleep, or cestivation, 

 akin to the winter sleep, or hybernation, of the 

 tortoise embryo. 



