Page:Popular Science Monthly Volume 63.djvu/40

36 lift its body by means of the paired fins, and these would then serve after the fashion of the arms and legs of a quadruped as the fish 'walked' slowly about, alternating the forward and backward movements of its extremities. This condition is illustrated in Fig. 4, in which the bend of the arms and legs, where they support the weight of the fish is shown satisfactorily. In this figure, which, together with Figures 5 and 6, were photographed from almost directly above the fish, one observes that the strain upon the limbs falls, not upon their

tips, but near the middle. Thus one notes in Fig. 6 that the tip of the right-hand pelvic limb curls upward and is free from the bottom. One observes especially in Fig. 3 the stress upon the left pectoral limb, which causes it to be bent almost at right angles in an elbow-like