In the earthworms, on the other hand, this coat is thick and composed of many layers.
Many of our native species spend the day lurking beneath stones, and sally forth at night in pursuit of their prey, which consistsof small insects, earthworms and snails.
They are disposed in two groups on either side, corresponding in the Polychaeta to the parapodia; the two bundles are commonly reduced among the earthworms to two pairs of setae or even to a single seta.
The prevalent number of testes is one pair in the aquatic genera and two pairs in earthworms. But there are exceptions; thus a species of Lamprodrilus has four pairs of testes.
Among the aquatic Oligochaeta and many earthworms (the families Lumbricidae, Geoscolicidae and a few other genera) the spermathecae are simple structures, as has been described.