《史记·七十列传·龟策列传》
神龟出自长江水中，庐江郡每年按时把二十只身长一尺二寸的活龟缴纳给太卜官，太卜官便在吉日剔取龟的腹下甲。
神龟出於江水中，庐江郡常岁时生龟长尺二寸者二十枚输太卜官，太卜官因以吉日剔取其腹下甲。
The spirit turtle is born in the waters of the Yangtze River. Every year the Lujiang prefecture gives the Grand Astrologer twenty live turtles that are a foot and two cun long. The Grand Astrologer then takes the lower half of their shells on an auspicious day.