Creatures

that have two winglets or fins, or that have none at
all like serpents, move all the same with not less than four points of
motion; for there are four bends in their bodies as they move, or
two bends together with their fins. Bloodless and many footed animals,
whether furnished with wings or feet, move with more than four
points of motion; as, for instance, the dayfly moves with four feet
and four wings: and, I may observe in passing, this creature is
exceptional not only in regard to the duration of its existence,
whence it receives its name, but also because though a quadruped it
has wings also.