common in most animals that live largely in the dark—the white fish of the Kentucky caves, for instance. Then the large eyes and their capacity for reflecting the light—a common feature of nocturnal eyes, witness the owl and the cat. And finally the evident confusion in the sunlight, the hasty flight toward dark shadow, and the carriage of the head while in the light, re-enforced the idea of an extremely sensitive retina.
"Beneath my feet, then, the earth must be tunneled out to an enormous extent, and in these caverns the new race lived. The presence of ventilating shafts and wells all along the hill slopes—everywhere, in fact, except along the river valley—showed how universally the ramifications of the underworld extended.
"And it was natural to assume that it was in the underworld that the necessary work of the overworld was performed. This was so plausible that I accepted it unhesitatingly.