Below is a paper by an American scholar whose interest was caught by the carving of this image of a mermaid at Clonfert Cathedral. In her essay, the late Patricia Radford examines the symbolism of the mermaid and what her image may signify within the context of the church.
Patricia Radford (d. 2003) Curator/Lecturer Oklahoma State University
For several years I have been engaged in research involving imagery sculpted on the medieval churches of Ireland. During one trip there, while I was visiting St. Brendan's Church at Clonfert, County Galway, my companion called my attention to a lovely image of a mermaid located on a pier of the chancel arch. Initially, I was surprised to see the mermaid image here at all, bare as the piers were of much else in the way of decoration. This also seemed a peculiar placement in light of the symbolic importance of the chancel arch as a liminal marker and sparked a new line of inquiry for me. The usual interpretation of mermaids is that they are images of lust and sexuality intended to caution the faithful against related sins. But perhaps there is a deeper meaning or an alternate meaning - or even a dual meaning for these images. That is what this paper will explore, along with the history of the mermaid in art.
The earliest known depiction of a mermaid dates back to the 18th century BC on a Babylonian sealstone. Classical references to creatures that are half-human and half-sea creature include the mythology of the gods Nereus and Triton. Nereus is often shown with a trident and was reported to appear to humans in many forms. Depictions of Triton sometimes show him with a single tail while in others he has two. These, however, are male images.
From the Classical period, female creatures associated with the sea or water include Scylla, the half-human, half sea-monster who consumed six of Odysseus' sailors in Homer's Odyssey, and the Sirens, again from the Odyssey, against whose seductive songs Odysseus caused himself to be lashed to the mast and his sailors' ears plugged with wax lest they be tempted to guide the ship and his comrades into their diabolical clutches. Greek mythology and lore are filled with tales of nereids, water nymphs, naiiads, and all manner of female water creatures. Although the Sirens were not possessed of fish tails, they were intimately associated with the sea. Despite their basic physiological differences from mermaids, Beryl Rowland asserts that " . . . in the Middle Ages, the features of mermaids and sirens become confused."  When beliefs about the physiology of mermaids and sirens become muddled, their symbolism becomes intricately entwined. Sirens, earlier thought of as having the bodies of birds, had come to be seen as anatomically identical with our conception of mermaids by the medieval period. As a result, we can safely say that these early Classical legends had a great deal of influence upon notions of mermaids throughout Western Europe and within the Church. It is equally likely that they have some bearing upon early Irish tales of mermaids too.
However, Irish tales tend to be more romantic than mermaid legends elsewhere. Known as merrows or muiroighe from 'muir' meaning sea and 'oigh' meaning maiden or youthful woman, these creatures were believed to have the ability to assume human form. The most common mermaid motif in early Irish literature involves the marriage between a mermaid or merrow and a mortal.  Typically, the legends describe a mortal who happens upon a group of these creatures who have shed their sea-skins or enchanted red caps to play along the beach. The mortal confiscates one of the skins or caps and hides it. Upon his return to the beach, he finds a lovely young woman who is searching desperately for the lost item so that she may transform back into a mermaid and join her companions in the sea. Instantly enamored of the maiden, the mortal comforts her and offers her the protection of his home as his wife. Seeing no other course, the mermaid-now-human consents. Many years pass and, after bearing the man several children, the wife happens across her enchanted cap or sea-skin one day, hidden by her husband many years prior. She returns to the beach, dons it, and returns to the sea, leaving her mortal husband and children to mourn her loss. Interestingly, several old Irish families trace their lineage to mermaids or muiroighe and include images of them on their family crests and arms.
From various of the annals of Ireland, including the Annals of Ulster and the Annals of the Four Masters, come reports of the capture of mermaids in the years 558, 571, 887, and 1118. Of these, the most famous tale is that of Liban, daughter of Eochaidh, who was spared when the flooding of Lough Neagh drowned her family around 90 A.D. She lived as a human for many years in a cave below the sea prior to her transformation into a mermaid. Once transformed, her singing so enchanted the denizens of Ulster that she was captured and placed on display. In one version, a certain young cleric named Beoc was so charmed by her singing that he asked her to be buried in the same coffin with him upon her demise. She was supposedly baptized "Muirgen" by St. Comgall of Bangor (Muirgen means 'born of the sea' or 'daughter of the sea.') As a result of several miracles associated with her, she became known as St. Murgen.
Thus the literature of early Ireland tells many tales of these half-fish, half-human creatures. From these stories, we glean that mermaids were invariably beautiful, sexual creatures described as having olive skin and webbed fingers, and whose lovely singing irresistibly lured mortal men  - even holy men such as Beoc!
This is in keeping with the Greek tradition of the sirens in the Odyssey whose beauty and glorious songs lulled hapless sailors to sleep and brought their ships crashing upon the rocks. The traditions diverge, however, regarding their relationships with humans.
While the sirens were malevolent beings and Greek mermaids were sometimes helpful but always elusive, Irish muiroighe were reported to have long-term relationships with mortal men through marriage and the bearing of their children or even, as in Liban's case, becoming saints. Contrasted with this early Irish notion of the mermaid as being relatively benign is the tradition of the mediaeval Christian Church. The Church saw the mermaid as a symbol of vanity and lust, of sexual display, and seduction and temptation leading to damnation. To enhance this meaning, she is usually depicted, as at Clonfert Cathedral, with a comb and mirror.  Lust is, of course, one of the Seven Deadly Sins.
Mermaids are often shown swimming among fish or sometimes holding one. At St. Mary's Priory, Clontuskert, she holds a starfish, a symbol of Christ or Christians. Where images of mermaids swimming with fish occur, it is clear that the intended meaning relates to the notion of temptation and is a warning lest the pious, represented by the fish, be lured by the Deadly Sin of lust. Where a mermaid is shown holding a fish or starfish, it is meant as an image of a Christian soul captured by lust. The inevitable conclusion is that the unfortunate soul yielded to temptation and is now damned. The message is cautionary - a warning so that the faithful will not be similarly seduced. Certainly this is the intended meaning of the 15th century mermaid carved on the chancel arch at St. Brendan's Cathedral at Clonfert. Located at approximately eye level, her placement is such that she is very visible from the nave. At about ten inches high, she can be seen from as far back as the middle of the small church. Although she appears on the right pier as viewed from the nave, she is on the soffit, facing the passageway rather than the nave itself. Her placement situates her at the priest's left as he stood facing the congregation. Evil was associated with the off- or left-hand side from ancient times.
Directly above the mermaid at Clonfert, and at many other locations including Clontuskert, is a beautifully carved, symmetrical knot. Knotwork in Irish and Celtic art has protective associations, so it seems the purpose of this motif is to protect the viewer from the mermaid's dangerous pull since merely gazing upon the creature might incite lust. At Clonfert, on the pier opposite the mermaid, at the priest's right, are three carved angels. It is typical of Irish churches that images associated with good are placed so that they can be seen to balance the potential evil of images of warning, such as mermaids. It is the nature of medieval art that an image may have multiple layers of meaning.
Recognition of this raises the possibility that images of mermaids may have meanings beyond the obvious sexual associations. It is my position that this is the case, especially when the mermaid is pictured with a comb and mirror, as seen in a relief on the steps of the Country Club in Galway (not it's original location, and the date records when the mermaid was moved to this location, not when she was carved). According to Barbara Walter, the mermaid's act of combing her hair was believed to be a form of spell-casting or magic-making.  Through the act of combing her hair, she was drawing strength and power to herself. So, images of mermaids with combs seem to be a clear reference to the weaving of a spell upon hapless mortals, the usual interpretation. Certainly a woman's hair was seen as potent source of feminine power. One need go no further than tales of Medusa and Rapunzel to see this. But, also, the widespread custom in early Europe of combing the bride's hair on the night before or the day of her wedding, suggests this. Hair, because of its ability to re-grow relates to re-birth. Meanwhile, the taming of a bride's hair through combing, coupled with the custom of married women wearing their hair "tamed" by putting it up rather than wearing it down and loose, suggests the power associated with it. Hair that was put up or covered with a cap could, metaphorically, be seen as lost - along with any power it was believed to possess. Hair, then, is associated with vital female forces, best harnessed once a woman comes of age.
Yet within the Church, priests practiced a ritual of purification of body and soul that involved combing the hair.  Special liturgical combs were used for this rite. They were rectangular with teeth arranged along both sides, many bearing Christian motifs, their overall form very much like the comb held by the Clonfert mermaid and others. Believed to have begun as early as the 4th century, this priestly ritual is documented as late as the 16th century in Western Europe and continues today within the Greek Orthodox Church. The placing of such a liturgical comb in St. Cuthbert's tomb in the 11th century indicates that the ritual was known and practiced in the Irish church as a form of cleansing prior to the celebration of Mass.
Therefore, as with so much of medieval art, the Irish mermaid with her comb and mirror, along with her obvious associations with water, can be interpreted as bearing various levels or nuances of meaning. Mermaids can be interpreted as temptresses who seduce the weak into the deadly sin of lust and, at the same time, a reminder of salvation through the sacrament of baptism.
Images of mermaids are placed at significant boundaries of Irish churches, separating secular from holy space at entrances or, as at Clonfert, dividing the nave from the chancel through placement on the chancel arch. A graphic reminder of the weakness of man, they also point to his need for salvation through the Church and the sacrament of baptism. 
Patricia Radford, M.A., lectured art history at Oklahoma State University where she was also Curator of Visual Resources. INSIGHT is grateful to her sister, Louisa, and her father, Robert, for permission to publish this paper.
1. Beryl Rowland. Animals with Human Faces: A Guide to Animal Symbolism. Knoxville: University of Tennessee Press, 1973, p. 140.
2. Sean O'Suilleabhan. Folktales of Ireland. Chicago: University of Chicago Press, 1966, pp. 272-273.
3.Jim Higgins. Irish Mermaids: Siren, Temptresses and their Symbolism in Art, Architecture and Folklore. Galway: Crow's Rock Press, p. 28.
4. Higgins, p. 13.
5. Gertrude Grace Sill. A Handbook of Symbols in Christian Art. NY: MacMillan, 1975, pp. 22-23.
6. Barbara Walter, The Women's Dictionary of Smbols and Sacred Objects, 1st edition. (San Francisco: Harper & Row, 1998), p. 129.
7. Sheila K. Redmon, "From the Bearer of the Rising Goddess to the Bearer of the Rising Soul: They Symbolism of Scallop Shells in Early Medieval Art," found in Proceedings of the Ninth Annual Meeting of the Oklahoma Conference of Art Historians, edited by Gay Clarkson & Patricia Radford (Stillwater, OK: Oklahoma State University Department of Art, 2000), p. 71.
8. Arnould Locard, Recherces historiques sur la coquille de pèlerins. (Lyon: 1888), pp. 75-76.