Each testis communicates by means of an efferent duct with a common collecting duct of its side of the body, which opens on to the exterior by means of a protrusible penis, and to which is sometimes appended a seminal vesicle.
Piercing jaws modified and reduced, a tubular, protrusible suckingtrunk being developed; mouth with hooks.
The male organs are usually a testis, a large seminal bladder and a protrusible penis.
The former leads to a protrusible pharynx (B), from which the oesophagus opens into a wide intestinal chamber with branching lateral diverticula.
The genus Rana may be defined as firmisternal Ecaudata with cylindrical transverse processes to the sacral vertebra, teeth in the upper jaw and on the vomer, a protrusible tongue which is free and forked behind, a horizontal pupil and more or less webbed toes.
Leeches without biting jaws possess a protrusible proboscis, and generally engulf their prey, as does the horse leech when it attacks earthworms. But some of them are also ectoparasites.
The terminal part of the male ducts may be protrusible and act as an intromittent organ, or this function may be discharged by some of the appendages, as, for instance, in the Brachyura.
Canal sometimes with protrusible proboscis; never with gizzard or oesophageal glands; intestine with caeca as a rule.
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.
This may be associated with mud-eating habits; but it is not wholly certain that this is the case; for in Chaetogaster and Agriodrilus, which are predaceous worms, there is no protrusible pharynx, though in the latter the oesophagus is thickened through its extent with muscular fibres.