very short and articulated with the skull far in front of the ends of the horns. No trace has been found of limbs, and the vertebræ interlock like those of the modern snakes; from this it is probable that these animals were limbless and snake-like in form, but they must have presented a most peculiar appearance with the slender body and enormous head. It is hardly possible that the animal could have raised its head from the ground except by an occasional and violent effort, for the skull was solid and relatively very heavy. Probably the animal was purely aquatic in habit and, lying in the mud of the bottom, wriggled forward, pushing its great head through the slime, from which it gathered the vegetation and small shell fish which formed its food. The position of the eyes and nostrils on the top of the skull renders this position the more certain. On the banks of the streams the amphibians took yet another form, for here they donned a complete coat of mail similar to that of the small reptile.
Imperfect as our knowledge still is of this wonderful group of animals, enough is already known to show how fully strife and warfare filled the world's history even at the beginning, and how every possible advantage of tooth or limb or armor was necessary for success.