pond-weed: A genus of the tetragynia order, belonging to the tetrandria class of plants; and in the natural method ranking under the 15th order, Inundata. There is no calyx; but four petals; no style, and four seeds. There are 12 species, all of them floating vegetables on the surfaces of stagnant waters, affording an agreeable shade to fish, and food to cattle.

POTAMON or Potamo, was a philosopher of Alexandria. He kept a middle course between the skepticism of the Pyrrhonians and the presumption of the dogmatists; but attached himself to none of the schools of philosophy of his time. He was the first projector of the Eclectic sect; for though that mode of philosophizing had been pretty common before, he was the first that attempted to institute a new sect on this principle. "Diogenes Laertius relates, that not long before he wrote his Lives of the Philosophers, an Eclectic sect, ἐκλεκτικοί, had been introduced by Potamo of Alexandria, who selected tenets from every former sect. He then proceeds to quote a few particulars of his system from his Eclectic institutes, reflecting the principles of reasoning, and certain general topics of philosophical inquiry; from which nothing further can be learned, than that Potamo endeavoured to reconcile the precepts of Plato with those of other masters. As nothing remains concerning this philosopher besides the brief account just referred to in Laertius, an obscure passage in Suidas, and another still more obscure in Porphyry; it is probable that his attempt to institute a school upon the Eclectic plan proved unsuccessful. The time when Potamo flourished is uncertain. Suidas places him under Augustus; but it is more probable, from the account of Laertius, that he began his undertaking about the close of the second century."