Amid their numerous and varied calls could be distinguished the "ll-l-luk" of the tree-toad (_Hyla versicolor_); and from the aquatic plants, that lined the spring close by, came the merry chirrup of the _Hylodes gryllus_, or "Savanna cricket." Far up among the leaves of the oaks the little green tree-frog repeated his tinkling bell-like note that fell with a pleasant sound upon the ear.

But all these were the usual voices of the night--the voices of the southern forest--and they produced no strange impression upon the listening hunters.

The call of the _Hyla_, indeed--loud and oft-repeated as it was--warned them that a rain-storm was near; and the darkness of the sky above confirmed the warning.
But it was not these sounds that had caused Marengo to spring up with such a savage growl; and the boys continued attentively listening to discover what it could have been.
The dark aisles of the forest sparkled with moving lights.

The fire-flies were abroad in thousands; and their phosphoric lamps, more than usually luminous, also betokened the approach of a rain-storm.
As the young hunters gazed, other lights attracted their attention, causing them to hold their guns in readiness.

These lights were very different from those of the insects.