in medicine and surgery, a tumour in the pelvis, arising from a collection of water.

HYDROPHANÆ, in natural history, a genus of semi-pellucid genus, composed of crystal and earth; the latter ingredient being in large proportion, and mixed imperfectly. imperfectly, as in the chalcedony; and giving a general cloudiness or mistiness to the stone, but of so imperfect and irregular an admixture, as not to be capable of so good a polish as the chalcedony; and appearing of a dusky and foul surface, till thrown into water, in which they become lucid, and in some degree transparent, either in part or totally; also changing their colour, which returns to them on being taken out of the water.

To this genus belong the oculus beli of authors, or whitish-grey hydrophanes, variegated with yellow, and with a black central nucleus; and the oculus mundi, or lapis mutabilis, which is likewise a whitish-grey kind without veins.