Three major heroic families remain to be considered, the Atlantids, who were descended from the seven daughters of Atlas, the Asopids, who were descended from the many daughters of the Peloponnesian river-god Asopos, and finally the Arcadian royal family. As in the case of the Pelopids, the first two families are of especial interest in relation to the origin and ancestral background of leading figures in the Trojan War. The family of Helen at Sparta and the family of Priam and Paris at Troy were brought together into the same genealogical system as two different branches of the Atlantid family (along with the Pelopids indeed, through a female line); and in the posthomeric tradition at least, the two greatest warriors in the Greek expeditionary force, Achilles and Aias (Ajax), were bracketed together as cousins of common Asopid descent. Both families were quite extensive, however, and will be considered in their full extent. The daughters of Atlas are also of some interest in their own right in their common nature as the Pleiades. The Arcadian royal family, which was descended from Pelasgos, the earthborn first man of that mountainous region, was rather similar in character to the Athenian royal family in so far as few of its members played any major role in heroic saga and it was primarily associated with a distinctive body of local legend.
Atlas, a son of the Titan Iapetos (see p. 49), managed to father a sizeable family even though he had to hold up the heavens; for his wife Pleione, daughter of Okeanos, bore him seven notable daughters, who were of twofold significance. Under their collective name of the Pleiades, they were identified with the seven stars of the splendid star-cluster of that name in the constellation of the Bull; and under their individual names, they were of genealogical importance as the founders of the various branches of one of the great families of heroic mythology, the family of the Atlantids. All but one of them bore children to major gods; and one, Maia, even became the mother of an Olympian god. Although we will be concerned