So I was right. My nymph with the seashell is actually by Bouguereau, as I had originally noted. Its name is Femme au Coquillage, the Woman with the Shell. I download images I might use in class, and try to make the correct attributions, but I do make mistakes, in spelling and in dates. Also, some of the sites I download from are themselves prone to error. But we try to fix them, and to learn.
This ghostly image is an artist's study, recently made available for sale by Sotheby's. The reflecting pool below her knees is missing.