This spider was first seen in a potted petunia. Next thing I knew it was flying about like a trapeze artist, demonstrating some pretty impressive aeronautical skills.
It was very small (maybe about the size of a Canadian dime, with its leg-span included) and had a dark upper abdomen with a white stripe around its side (or rather a whitish lower abdomen perhaps).
Arachnids are a class (Arachnida) of joint-legged invertebrate animals in the subphylum Chelicerata. All arachnids have eight legs, although the front pair of legs in some species has converted to a sensory function, while in other species, different appendages can grow large enough to take on the appearance of extra pairs of legs. The term is derived from the Greek word ἀράχνη (aráchnē), meaning "spider".