An example of a comparatively simple epigyne is that of "Pirata montanus". It consists of a nearly plain plate, with the openings of the spermathacae near the posterior lateral corners. A somewhat more complicated form is illustrated by the epigyne of "Trabeops aurantiacus". In this species, the plate is depressed or furrowed longitudinally, and the depressed area is divided by a ridge-like elevation, which divides the depression into two furrows or channels, each of which leads to the opening of the spermatheca of the corresponding side. This ridge-like elevation is called the "guide", as its function "seems clearly to be that of a guide to the male embolus, controlling the course of the latter and facilitating its entrance to the spermatheca." In many cases the guide extends laterally on each side at its posterior end. This is true to a slight extent in the epigyne of "Trabeops", but more markedly so in that of many species of "Geolycosa", where the lateral expansions often conceal the openings of the spermathecae, as in the epigyne of "Geolycosa pikei".