One of the capitals in the romanesque Église Saint-Géraud in Lempdes-sur-Allagnon, shows this smiling colourful mermaid. She looks so different from the mermaids I found sofar. Just small addons to her feet make clear that there are fins. On the right a bearded face. There is an article on mermaids in Ireland, titled "Lusty Ladies" . Maybe she is a "Lusty Lady". It was so dark in this corner of the church, that I used a little torchlite.

Here is the article:
homepage.eircom.net/~archaeology/three/mermaid.htm

Here is the