We don't know how many strings the original Lyras had. By the time of Terpander (8th-7th cent. BC) Lyra was a seven stringed instrument and from many ancient sources we know that this type remained in use for a long time during the classical period. The addition of an eighth string in the 6th century BC is credited by Nicomachus of Gerasa to Pythagoras. By the fifth century there were Lyras with anything from 9 to 12 strings. The strings (neura) were made of animal gut of sinew, but there are also references of strings made of linen or hemp. Lyra was mainly used for the musical education of the young, and by amateur players in general.
Cithara plucked instrument with 5 strings originally, but later with as many as 12 strings. Cithara was bigger than the Lyra and it was the principal concert instrument played by professional musicians, the citharodes. According to Plutarch, cithara was designed by Cepion, a student of Terpander. Many instrument names like guitar, cittern, zither etc. derive from the word cithara.
Barbitos or Barbiton is an instrument of the Lyra family and resembles a Lyra, but it has longer arms and narrower sound box. Musicians of the School of Lesbos, like Alcaeus and Sappho, are frequently depicted in vases playing the Barbitos.
Phorminx probably the oldest of the Cithara type instruments. From references in ancient sources (Homer, Hesiod, Aristophanes) we know that...