The male ducts are either one pair or two pairs, which open by a common and complicated efferent terminal apparatus furnished with a protrusible penis.
In the lastmentioned worm the funnels of the anterior nephridia are small and but few celled; it is only the nephridia in and behind the 17th segment of the body which are particularly large and with a sinuous margin, which recall the funnels of the gonad ducts (i.e.
These ducts therefore have not their exact counterparts in the Oligochaeta, unless we are to assume that they collectively are represented by the seminal vesicles of earthworms and the vasa deferentia.
The function of nitrogenous excretion was not therefore a necessary part of the view - though it may be pointed out that there are grounds for believing that the gonad ducts are to some extent also organs of excretion (see below).
The efferent ducts are ciliated, and there is a patch of cilia at the point where they communicate with the cavity of each testis.
The eye is provided with a nictitating membrane or third eyelid, at the base of which open the ducts of the Harderian gland.
The intervening segments contain the genitalia, which are on the Oligochaeta plan in that the gonads are independent of their ducts and that there are special spermathecae, one pair.
The coelom opens to the exterior by ducts which are primarily genital ducts by which the ova or sperms are discharged.
Thus the condition in the Dermaptera is more primitive than in any other Pterygote order except the Ephemeroptera (Mayflies) which are still more generalized, the primitive mesodermal ducts (oviducts and vasa deferentia) opening by paired apertures as in the Crustacea.
It is a noteworthy fact that other tubes in these same terrestrial Arthropoda - namely, the ducts of glands - are similarly strengthened by a chitinous cuticle, and that a spiral or annular thickening of the cuticle is developed in them also.