Freddie nodded his head, and then, remembering that Flossie could not very well see his motions in the darkness he said:
"Yes, I heard it. I wonder——"
"Hark!" whispered Flossie. "There it goes again!"
CHAPTER XXI
"HERE COMES SNAP!"
The sound came once more through the darkness to the little Bobbsey twins, and as they listened to it Flossie and Freddie looked at one another in surprise. They could just dimly make out the faces of each other in the dimness.
"Mamma! Mamma!" cried a voice, for it was a voice that had caused the queer sound; yet it did not sound like the voice of man, woman or child. "Mamma! Mamma!" it cried.
"Hear it?" asked Flossie again.
"Yep," answered Freddie. "It's a little boy or girl—like us—an' it's in this cave. I guess lots of childrens get lost here like us. Now I'm not afraid."