One of the classes into which the insects are divided is termed _Myriopoda_, from the fact that the individuals which compose it are supplied with a seemingly endless number of locomotive organs. The centipedes and millepedes, “hundred” and “thousand legs,” are the names by which they are most commonly known. The body is long and cylindrical in the genus _Geophilus_, being made up of from thirty to two hundred segments, each bearing a pair of short feet. In the Eastern States _Lithobius Americanus_, Wood., is perhaps the most familiar form, and often found under old logs. Some of the centipedes are very poisonous. Such a one is _Scolopendra heros_, Girard., the poison being stored in two enormous fangs. In Southern California I have found extremely large specimens of this genus. In the East Indies _Scolopendra gigantea_, Linn., attains a length of nine inches, and is a most repulsive appearing creature, and so dreaded that the most extravagant stories are told as to its power. A native informed me, who evidently believed his statement, that a man died near him from having one merely walk over him. The bite is undoubtedly poisonous, as is that of many of our common spiders; but I never could find an authentic case where it had resulted fatally. As hideous as they are in certain parts of South America, a huge species, which attains a length of a foot, is eaten; the native children, according to Humboldt, tearing off the heads, and devouring the remainder with evident enjoyment. There are about eight hundred species of _Myriapods_, and among them is one, the _Geophilus electricus_ of Europe, that is positively luminous; though Phipson, referring to them as _Scolopendræ_, gives two luminous species, _S. electrica_, Linn., of Europe, and _S. phosphorea_ of Asia. Specimens of the former, observed in fields at night, have been compared to minute pieces of red-hot coal, so vivid was the light. Probably the finest spectacle of the luminosity of these insects was observed by M. Audouin, at Choissy-le-Roi, near Paris. Noticing a light upon the ground in a chiccory field, he ordered his man to turn up the earth, when the scene that followed is described as truly magnificent. The soil appeared as if it had been sprinkled with molten gold, the display being intensified if the insects were trodden upon or rubbed; in the latter case, streaks of light appeared, as if a bit of phosphorus had been placed upon the hands, the light being distinctly visible for twenty seconds.