Wallace collected more than 125,000 specimens in the Malay Archipelago (more than 83,000 beetles alone). Several thousand of them represented species new to science. One of his better-known species descriptions during this trip is that of the gliding tree frog "Rhacophorus nigropalmatus", known as Wallace's flying frog. While he was exploring the archipelago, he refined his thoughts about evolution and had his famous insight on natural selection. In 1858 he sent an article outlining his theory to Darwin; it was published, along with a description of Darwin's own theory, in the same year.