Linnaeus tells us, on the authority of Bartholinus, that, when the Octopus vulgaris is opened in the dark, a light so strong and splendid is emitted, as perfectly to illuminate the room.

I am not aware that any gasteropode is phosphorescent; but the Pholades, among the bivalves, are greatly so ; yet, for what purpose they light up their gloomy ceils, unless it be to allure some minute in- sect prey, it is hard to guess, for they themselves are " dark in light.

" Pliny says, the phosphoric fluid is so abundant in them, that it shines about the mouths of those who eat the Dactyli, shines on their hands, and even on their clothes, from drops falling thereon.

The Dactyli of Pliny have commonly been considered the same as the Pholas Z)actylus of Linnaeus; but the description given by the Roman naturalist will disturb no conjecture; and his Z)actyli may very possibly be the ikfytilus lithophagus (Lithodomus Cuvie?-), concerning which, Mr Charles Ulysses says, "that in the Bay of Naples the fishermen place the animal in the sun, and with it besmear their hands and faces at night, so as to illuminate them as with phosphorus.

" It is, however, among the Mollusca tunicata that the most considerable phosphorescent species are found.