"What are you on the track of now?" asked Nort.
"A Brontotherium," answered the professor.
"What did he say—a bronco?" asked Bud. "We've got some over at our place you can have for nothing," he added with a laugh. "They're not dead yet, though some of the boys who tried to ride 'em wish they were."
"A Brontotherium," explained Professor Wright, "is an extinct animal, something like the rhinoceros, but much larger—more than the size of an elephant, I hope to prove. There are indications that I may find the bones here."
"I hope you do," remarked Dick.
The boys wandered around the camp, and were about to leave the scene of the digging and excavating when Nort uttered an exclamation.
"What's the matter?" asked his brother.
"Look! There's Del Pinzo!" exclaimed Nort, and, surely enough, the figure of the wily Greaser or half-breed was seen moving among the men engaged by the professor to help him and his assistant in digging up fossil bones.
"You have that rascal again, I see, Professor," said Bud rather coldly.
"Well, he certainly is a great help," was the answer. "He has great influence over the Mexican laborers."