Same entry in Photius (Lexicon delta750), where Theodoridis obelizes the tranmitted headword draukalos; similar one in Hesychius delta2305.
Sophocles' (lost) play was named apparently from its chorus of drummers or tympanum-beaters (usually of the kettledrum associated with the cults of Dionysus and the Great Mother, and beaten with the hand): Sophocles fr.643 TGF vol.4.460 (= 585 Nauck). But the etymology given here is completely implausible, as is agreed by all philologists: forms from the word 'snake' begin drakon(t)-. Rather, it is from one of the two normal vocalisations of *drk-, the root of de/rkomai 'see', probably of a god or spirit who watches the court where the animals are kept. The aule is the initially open courtyard of a villa-type house.
The entry suggests that the epithet was associated with one of the daughters of Cecrops (kappa 1272), the mythical king of Athens, who was "of double nature" because he was half man, half snake (see images at web address 1 and web address 2). He chose Athena as the city's patron-goddess. His son Erichthonius was protected by a snake in a chest given to his three daughters to guard; they were killed or driven mad by the snake when they pried into the chest. These and other myths concerning the daughters of Cecrops are explored by Pearson (using Euripides, Ion 21ff., 271ff., Ovid, Metamorphoses 2.552ff. and other sources). There was a snake sacred to Athena on the Acropolis (see Pearson). Cadmus' daughters are normally called Agraulos (alpha 268), Herse (alpha 3863), and Pandrosos (pi 182). The last is also a cult name of Athena. Clearchus and Niceratus wrote comedies entitled Pandrosus.
For speculation on the role of Phineus in the plot of the play see the Loeb edition of the fragments (ed. H. Lloyd-Jones, 1996, pp.308-09). Some have suggested that it was a satyr-play.