“Nothing of the sort,” said the Professor, severely. “Living, as I do, in an educated and scientific atmosphere, I could not have conceived that the first principles of zoology were so little known. Is it possible that you do not know the elementary fact in comparative anatomy, that the wing of a bird is really the forearm, while the wing of a bat consists of three elongated fingers with membranes between? Now, in this case, the bone is certainly not the forearm, and you can see for yourself that this is a single membrane hanging upon a single bone, and therefore that it cannot belong to a bat. But if it is neither bird nor bat, what is it?”

My small stock of knowledge was exhausted.

“I really do not know,” said I.

He opened the standard work to which he had already referred me.