"A Mexican tickler!" cried Jack.
"That's what, and some one placed it under Petticoats' saddle blanket before the boy mounted," rejoined Bud solemnly.
"Poor beast! No wonder she cut up didoes," said Ralph.
"I should say not. Look at this."
The cowboy lifted the hind flap of Petticoats' saddle, and raising the blankets, showed her back raw and bleeding from the cruel roweling she had received.
"But however did that spur get there?" gasped Ralph.
"Not hard to guess. Can't you imagine?" asked Jack Merrill.
"No, unless——"
"It was that greaser you knocked out," Jack finished for him.
"Consarn the heathenish rattlesnake!" exclaimed the livery stable keeper, who had been among those to follow the wild chase of the canal-carried boys. "I seen him monkeying around your ponies just before he rode out of the barn. If I ever get my hands on him——"