I find them clustered in two heaps, without any attempt at order.

They have suffered less from the cold, thus huddled together.
'Tis an ill wind that blows nobody any good.

The severity of the night has caused the ring to break into two segments which will, perhaps, afford a chance of safety.

Each group, as it survives and resumes its walk, will presently be headed by a leader who, not being obliged to follow a caterpillar in front of him, will possess some liberty of movement and perhaps be able to make the procession swerve to one side.
Remember that, in the ordinary processions, the caterpillar walking ahead acts as a scout.

While the others, if nothing occurs to create excitement, keep to their ranks, he attends to his duties as a leader and is continually turning his head to this side and that, investigating, seeking, groping, making his choice.