THE REPTILES 199 
supposed to serve for the purpose of defense, and that it is 
in some way related to the poison-glands. This, however, 
is an error. The tongue is used primarily as an organ of 
- Fie. 119.—Tnatera (Sphenodon punctatus). 
touch, and in snakes especially it is almost continually 
darted in and out to determine the character of the animal’s 
surroundings. 
188. Egg-laying.—The eggs of the reptiles are relatively 
large and enclosed in a shell like a bird’s egg, the shell, 
however, being leathery rather than made of lime. These 
are deposited in some warm situation, and generally left to 
themselves to hatch. Under stones, logs, and leaves, or 
buried lightly in the soil, are the positions most frequently 
chosen by the lizards and snakes. The turtles almost inva- 
riably select the warm sand at the edge of the water, and 
after scooping a hole lay several perfectly spherical eggs, 
usually at night. The alligators lay upward of a hundred 
eggs about the size of those of a goose, and guard them 
jealously until and even after they hatch. On the other 
hand, the young of many lizards and snakes are born alive, 
the eggs being hatched within the body. 
Many reptiles are surprisingly slow in attaining maturity, 
and live to an age attained by few other animals. It isa 
well-known fact that turtles live fully a hundred years, and 
14 
