I will only venture to add the following remarks to the learned explanations of Professor Ideler. According to Pliny and Solinus, Atlas rises from the midst of a sandy plain (_e medio arenarum_), and its declivity affords pasture to elephants, which have undoubtedly never been known in Teneriffe. That which we now term Atlas is a long mountain ridge. How could the Romans have recognised one isolated conical elevation in this mountain range of Herodotus? May the cause not be ascribed to the optical illusion by which every mountain chain, when seen laterally from an oblique point of view, appears to be of a narrow and conical form? I have often, when at sea, mistaken long mountain ranges for isolated mountains. According to Höst, Mount Atlas is covered with perpetual snow near Morocco. Its elevation must therefore be upwards of 11,500 feet at that particular spot. It seems to me very remarkable that the barbarians, the ancient Mauritanians, if we are to believe the testimony of Pliny, called Mount Atlas _Dyris_. This mountain chain is still called by the Arabs _Daran_, a word that is almost identical in its consonants with _Dyris_. Hornius,[EP] on the other hand, thinks that he recognises the term Dyris in the word _Ayadyrma_, the name applied by the Guanches to the Peak of Teneriffe.[EQ] As our present geological knowledge of the mountainous parts of North Africa, which, however, must be admitted to be very limited, does not make us acquainted with any traces of volcanic eruptions within historic times, it seems the more remarkable that so many indications should be found in the writings of the Ancients of a belief in the existence of such phenomena in the Western Atlas and the contiguous west coast of the continent. The streams of fire so often mentioned in Hanno’s Ship’s Journal might indeed have been tracks of burning grass, or beacon fires lighted by the wild inhabitants of the coasts as a signal to warn each other of threatening danger on the first appearance of hostile vessels. The high summit of the “Chariot of the Gods,” of which Hanno speaks (the θεῶν ὄχημα), may also have had some faint reference to the Peak of Teneriffe; but farther on he describes a singular configuration of the land. He finds in the gulf, near the Western Horn, a large island, in which there is a salt lake, which again contains a smaller island. South of the Bay of the Gorilla Apes the same conformation is repeated. Does he refer to coral structures, lagoon islands (Atolls), and to volcanic crater lakes, in the middle of which a conical mountain has been upheaved? The Triton Lake was not in the neighbourhood of the lesser Syrtis, but on the western shores of the Atlantic.[ER] The lake disappeared in an earthquake, which was attended with great fire-eruptions. Diodorus[ES] says expressly πυρὸς εκφυτήματα μεγάλα. But the most wonderful configuration is ascribed to the hollow Atlas, in a passage hitherto but little noticed in one of the philosophical Dialexes