Which preposition to use with quatrefoils

at Occurrences 2%

The two windows of St. Lawrence's Chapel have a transom across the lights and a band of seven quatrefoils at the spring.

in Occurrences 1%

The earliest specimen is a reading desk, presented by the Mikado, with a slope for a book much resembling an ordinary bookrest, but charmingly decorated with lacquer in landscape subjects on the flat surfaces, while the smaller parts are diapered with flowers and quatrefoils in relief of lac and gold.

on Occurrences 1%

They are said to have been fixed within the quatrefoils on five sides, the remaining three being plain.

under Occurrences 1%

The church, which has been rebuilt, has a good tower, with pinnacled buttresses and a row of quatrefoils under the belfry storey.

Which preposition to use with  quatrefoils