(E-kid'-na). Half-woman, half-serpent. She was mother of the Chimæra, the many-headed dog Orthos, the hundred-headed dragon of the Hesperides, the Colchian dragon, the Sphinx, Cerberos, Scylla, the Gorgons, the Lernæan hydra, the vulture that gnawed away the liver of Prometheus, and the Nemean lion.
[She] seemed a woman to the waist, and fair But ended foul in many a scaly fold, Voluminous and vast.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Echidna from Infoplease: