Another qoute:

Speculum Regale (also called the King's Mirror, written in Norway around 1250): "Another prodigy called mermaid has also been seen there. This appears to have the form of a woman from the waist upward, for it has large nipples on its breast like a woman, long hands and heavy hair, and its neck and head are formed in every respect like those of a human being. The monster is said to have large hands and its fingers are not parted but bound together by a web like that which joins the toes of water fowls. Below the waist line it has the shape of a fish with scales and tail and fins. It is said to have this in common with the one mentioned before, that it rarely appears except before violent storms. Its behavior is often somewhat like this: it will plunge into the waves and will always reappear with fish in its hands; if it then turns toward the ship, playing with the fishes or throwing them at the ship, the men have fears that they will suffer great loss of life. The monster is described as having a large and terrifying face, a sloping forehead and wide brows, a large mouth and wrinkled cheeks. But if it eats the fishes or throws them into the sea away from the ship, the crews have good hopes that their lives will be spared, even though they should meet severe storms."