A sub-variety of the ætiological myth is the etymological myth, which takes as its starting-point a particular proper name and tries to explain the origin of it by a substructure of actual fact. The primitive history of Rome is rich in myths of this class also, and a multitude of the fables contained in it have been spun out of proper names. Such are the fables of Argos, Evander’s host; of the Argive colony in Rome; of the birth of Silvius Postumus in the forest; of the relations between the good Evander and the evil Cacus; the suckling of Romulus; the relation of the sucklings to the sacred fig-tree (_Ficus ruminalis_), the pretended origin of the Fossa Cluilia; the origin of the Tarquins from Tarquinii; the discovery of the head of Olus; the birth of Servius Tullius from a slave girl; the building of the Tullianum by the king of that name; the imbecility of Brutus; the burning of Scævola’s right hand; the conquest of Corioli by Coriolanus; and so forth. There is another variety of Roman legend which must be distinguished from the ætiological and etymological myth: the legend which may be described as the mythic garb of actual conditions and events, and which thus stands midway between legend and myth. To this class belong, for example, the legend of the Sibyl who comes to Rome in the time of the younger Tarquin, and would have him buy nine books of divine prophecies for a great price, and who, being mocked by him, burns three books before his eyes, and yet another three, and finally sells the three remaining books to the king for the price she had asked at the beginning. There is not the slightest doubt that this legend is based on a substratum of fact, the fact that the Sibylline prophecies were probably brought from Cumæ to Rome under the second Tarquin, but this fact is clothed in a garb of poetical fiction; it is a cross between legend and myth. The same may hold good of the number of the Roman kings; these seven kings stand for and figure forth the seven fundamental facts of the ancient (pre-republican) history of Rome which have been held in historic remembrance.