But, in the same motion, the Black’s flying head had veered; and his jaws had found a hold above Tam’s jugular. Again, with the normal dog, such a hold might well have ended the fight. But, the Providence which ordained that a collie should guard sheep on icy Highland moors also gave him an unbelievably thick coat, to fend off the weather. And this coat serves as an almost invulnerable armour; especially at the side of the throat. The Black’s teeth closed upon a quantity of tangled fur; but on only the merest patch of skin and on none of the under flesh at all.

Tam ripped himself free, leaving a double handful of ruff between the Black’s grinding jaws. As the mongrel spat out the encumbering gag of fur, Tam’s curved fang laid bare the scarred shoulder once grazed by Trask Frayne’s buckshot. And, in a rolling, fighting heap, the two enemies rolled over and over together on the dew-drenched grass.

Frayne’s gun was levelled. But the man did not dare fire. By that deceptive light, he had no assurance of hitting one dog without also killing the other. And, chafing at his own impotence, he stood stock-still, watching the battle.

Both dogs were on their feet again; rearing and rending in mute fury. No sound issued from the back-curled lips of either. This was no mere dogfight, as noisy as it was pugnacious. It was a struggle to the death. And the dogs realised it.

Thrice more, the Black struck for the jugular. Twice, thanks to Tam’s lightning quickness, he scored a clean miss. The third time, he annexed only another handful of hair.

With his slashes he was luckier. One of Tam’s forelegs was bleeding freely. So was a cut on his stomach, where the Black had sought to disembowel him. And one side of his muzzle was laid open. But the collie had given over such mere fencing tactics as slashing. He was tearing into his powerful and wily foe with all the concentrated fury of his month’s vain pursuit of vengeance.

The Black dived for the collie’s forelegs, seeking to crack their bones in his mighty jaws and thus render his foe helpless. Nimbly, Tam’s tiny white forefeet whisked away from the peril of each dive. In redoubled fury he drove for the throat. And the two clashed, shoulder to shoulder.

Then, amid the welter, came the final phase of the fight. The Black, as the two reared, lunged again for the collie’s hurt throat. Tam jerked his head and neck aside to avoid the grip. And, as once before, the Black changed the direction of his lunge. With the swiftness of a striking snake, he made the change. And, before the other could thwart or so much as divine his purpose, he had secured the coveted hold, far up on Tam’s left foreleg.

No mere snap or slash, this; but a death grip. The Black’s teeth sank deep into the captured leg; grinding with a force which presently must snap the bones of the upper leg and leave the collie crippled against a practically uninjured and terrible antagonist. The rest would be slaughter.