and defecation (the anus). In monotremes, only semen passes through the penis while urine is excreted through the male's cloaca. The monotreme penis is similar to that of turtles and is covered by a preputial sac. Male monotremes do not have a prostate or seminal vesicles.

Monotreme eggs are retained for some time within the mother and receive nutrients directly from her, generally hatching