After the auditorium the next great division of the theatre is the orchestra. This was the name given to the flat surface enclosed between the stage-buildings and the inside boundary of the auditorium. It was called the orchestra, or dancing-place’, because in Greek theatres it was reserved for the performances of the chorus.[350] In later times it was also called the Sigma, because its shape resembled the semicircular figure which was adopted in the fourth century as the symbol of the letter sigma.[351] In one place the word ‘konistra’ is employed to denote the orchestra.[352] Konistra means properly the arena of a wrestling-school. It would hardly be applicable as a term for the early Greek orchestras, which were used for music and dancing, but not for gymnastic contests. Probably therefore this meaning of the word was of late origin, and first arose in the Roman period, when Greek theatres occasionally became the scene of gladiatorial contests. Among the Romans the orchestra was given up to the spectators, and the performances of singers and dancers took place upon the stage. Hence the later Greek commentators and grammarians often used the word ‘orchestra’ improperly to denote the stage, which in Roman theatres had now become the actual dancing-place. This later signification of the term has given rise to much confusion. When a Greek scholiast speaks of the orchestra, it is necessary to look carefully to the context, to see whether he means the stage, or the orchestra in its proper sense.[353]