Males have a " V "-shaped pattern of scales just aft of the cloacal opening, which is not present in female skinks.
42.
The cloacal region has a blackish colour, while the chest, ventral parts of the limbs, and throat are a dirty yellowish colour.
43.
The female twists and moves her tail feathers to one side, while the mounted male twists his cloacal opening around the female's cloaca.
44.
After mounting the female, the male extends his cloaca by curving his back in an attempt to initiate cloacal contact between him and the female.
45.
Epidermal glands are located in the cloacal region of " A . alba " and are most likely used for reproduction and marking territory.
46.
Fertilisation is likely to be external as sirenids lack the cloacal glands used by male salamandrids to produce spermatophores and the females lack spermathecae for sperm storage.
47.
Males and females can only reliably be sexed during the breeding season by the presence of a brood patch in females or a cloacal protuberance in males.
48.
A bird penis is different in structure from mammal penises, being an erectile expansion of the cloacal wall and being erected by lymph, not blood.
49.
Both monotremes and marsupial moles are the only mammals with internal penises, located on the cloacal wall instead of outside of it as in other mammals.
50.
Most birds mate with the males balancing on top of the females and touching cloacas in a cloacal kiss ; this makes forceful insemination very difficult.
