There are a clitellum and sperm ducts which though like nephridia have a larger funnel and a less complexly wound duct.
When wings are present, the fore-wings are small firm elytra, beneath which the delicate hind-wings are complexly folded.
Now the kinetics of a medium in which the parts can have finite relative motions will lead to equations which are not linear - as, for example, those of hydrodynamics - and the phenomena will be far more complexly involved.
This deposition of bony matter progresses very rapidly, and although in young deer and the adults of some species the resulting antler merely forms a simple spike, or a single fork, in full-grown individuals of the majority it assumes a more or less complexly branched structure.
Border, are a series of somewhat irregular ridges developed on complexly folded and faulted crystalline rocks.