A very large number of animals have been recorded as having been employed in the gratification of sexual desire at some period or in some country, by men and sometimes by women. Domestic animals are naturally those which most frequently come into question, and there are few if any of these which can altogether be excepted. The sow is one of the animals most frequently abused in this manner.[51] Cases in which mares, cows, and donkeys figure constantly occur, as well as goats and sheep. Dogs, cats, and rabbits are heard of from time to time. Hens, ducks, and, especially in China, geese, are not uncommonly employed. The Roman ladies were said to have had an abnormal affection for snakes. The bear and even the crocodile are also mentioned.[52] The social and legal attitude toward bestiality has reflected in part the frequency with which it has been practiced, and in part the disgust mixed with mystical and sacrilegious horror which it has aroused. It has sometimes been met merely by a fine, and sometimes the offender and his innocent partner have been burnt together. In the middle ages and later its frequency is attested by the fact that it formed a favorite topic with preachers of the fifteenth and sixteenth centuries. It is significant that in the Penitentials,--which were criminal codes, half secular and half spiritual, in use before the thirteenth century, when penance was relegated to the judgment of the confessor,--it was thought necessary to fix the periods of penance which should be undergone respectively by bishops, priests and deacons who should be guilty of bestiality.