One dark night, about the beginning of December, while passing along the streets of the Villa de Natividade, I observed some boys amusing themselves with some’ luminous object, which I at first supposed to be a kind of large fire-fly; but on making enquiry I found it to be a beautiful phosphorescent fungus, belonging to the genus _Agaricus_, and was told that it grew abundantly in the neighbourhood, on the decaying leaves of a dwarf palm. Next day I obtained a great many specimens, and found them to vary from one to two inches and a half across. The whole plant gives out at night a bright phosphorescent light, of a pale greenish hue, similar to that emitted by the larger fire-flies, or by those curious soft-bodied marine animals, the _Pyrosomæ_; from which circumstance, and from growing on a palm, it is called by the inhabitants “Flor do Coco;” the light given out by a few of these fungi, in a dark room, was sufficient to read by. It proved to be quite a new species, and since my return from Brazil, has been described by the Rev. Mr. Berkeley under the name of _Agaricus Gardneri_, from preserved specimens which I brought home. I had already named it _A. phosphorescens_, not being aware at the time I discovered it, that any other species of the same genus exhibited a similar phenomenon; such, however, is the case in the _Agaricus olearius_ of De Candolle; and Mr. Drummond, of the Swan River Colony in Australia, has given an account of a very large phosphorescent species occasionally found there.[11]