Examples from the Web for ink sac
They are without an ink-sac, and have the foot divided into lobes bearing sheathed tentacles.
In certain cases remains of the arms provided with hooks, and of the ink-sac, have been recognized.
The ink-sac, absent in Nautilus, is a rectal caecum developed from its dorsal wall.
The ink taken from the ink-sac of Sepia is an article of commerce.