Also known as the sulcus spermaticus, a lengthwise groove along the penis that transfers semen during ejaculation. The groove is effectively sealed into a tube due to erectile swelling, and may appear as a sort of "seam" along the erect penis. Depending on the species, it may be straight or helical in shape.

Typically found in non-mammalian penises, such as hemipenes and crocodilian_penis, in place of a urethra.

See also:

• cloaca
• animal_penis
• hemipenes
• crocodilian_penis
• turtle_penis
• duck_penis