More than once, as these chanced to cross one another's path, that same long-drawn hiss quavered out into the dark silences.
And now Brice's nostrils were assailed by a sickening smell as of crushed cucumbers.

And at the odor his fists tightened in new fear.

For no serpents give off that peculiar odor, except members of the pit-viper family.
"They're not rattlesnakes," he told himself.

"For a scared or angry rattler would have this room vibrating with his whirr.
We're too far south for copperheads.

The--the only other pit-viper I ever heard of in Florida is the--cotton-mouth moccasin!" At the realization he was aware of a wave of physical terror that swept him like a breath of ice.
Without restoratives at hand the moccasin's bite is certain death.