《水经注·卷三十七》
县里江水中有潜牛，形状像水牛，上岸相斗，角软以后又潜入江水中，待到角硬后再出来。
县江中有潜牛，形似水牛，上岸斗，角软还入江水，角坚复出。
In the river of the county, there are diving cows, which resemble water buffaloes. They come ashore to fight, and when their horns become soft, they dive back into the river water, waiting for their horns to harden before coming out again.