National Geographic : 1944 Nov
The National Geographic Magazine Mrs. A. M. Awl Nature's Miniature Submarine, the Four-eyed Fish, Has Twin Periscopes Each bulbous eyeball of Anableps dowei, the four-eyes, is divided in two. The upper part, adapted for air vision, projects from the water to scan the surface for floating food; the lower eye looks for sub marine enemies. Difference in focus is compensated for by bifocal lenses. Lacking eyelids and tear glands, Anableps must constantly dip its eyes under water to keep them moist (page 604 and Plate VIII). Eggs and Corn in Hot Springs Near Ahuachapin 606 What's Cooking?