The Dolphin and the Deep (1968) - a collection of 3 fantasy novelets by Thomas Burnett Swann. A modified version of "The Manor of Roses" was used in the fix-up The Tournament of Thorns; the others don't appear in any other Swann collection. This paperback is the only edition.

The Dolphin and the Deep
The Manor of Roses
The Murex

"The Manor of Roses" appeared in Magazine of F&SF (1966); the other 2 came from the British magazine Science Fantasy (1963/1964.)