This was the _ground rattle-snake_, which could be seen, coiled up, and basking in the sun, or gliding among the mounds, as if searching for his prey.

Basil noticed that it was a different species from any of the rattle-snakes he had seen--differing from them in its shape and markings, but equally vicious in its appearance and habits.

It was the _Crotalus tergeminus_--found only in barren grounds, such as those inhabited by the prairie-marmot.
Basil could not help falling into a train of reflection about this varied community of creatures.

Were they friends to each other?
or did they form a chain of destruction, preying upon one another?
Friends they could not all be.

The marmots lived upon grass; and the lizards upon insects and prairie-crickets, of which there were numbers around.
Upon these, too, no doubt, the tortoises supported themselves; but upon what fed the owls and snakes?
These questions puzzled Basil.