76 



ANIMAL LOCOMOTION. 



In the Sea-Bear (Otaria juhata) the anterior extremities 

 attain sufficient magnitude and power to enable the animal to 

 progress by their aid alone; the feet and the lower portions of 

 the body being moved only sufficiently to maintain, correct, or 

 alter the course pursued (fig. 73). The anterior extremities are 

 flattened out, and greatly resemble wings, particularly those of 

 the penguin and auk, which are rudimentary in character. 

 Thus they have a thick and comparatively stiff anterior 

 margin ; and a thin, flexible, and more or less elastic posterior 

 margin. They are screw structures, and when elevated and 

 depressed in the water, twist and untwist, screw-fashion, 

 precisely as wings do, or the tails of the fish, whale, dugong, 

 and manatee. 



Fig. 37.— The Sea-Bear {Otaria juhata), adapted principally for swimming 

 and diving. It also walks with tolerable facility. Its extremities are larger 

 than those of the seal, and its movements, both in and out of the water, 

 more xaried.— Original. 



This remarkable creature, which I have repeatedly watched 

 at the Zoological Gardens^ (London), appears to fly in the 

 water, the universal joints by which the arms are attached to 

 the shoulders enabling it, by partially rotating and twisting 



1 The unusual opportunities afforded by this unrivalled collection have 

 enabled me to determine with considerable accuracy the movements of the 

 various land-animals, as well as the motions of the wings and feet of birds, 

 both in and out of the water. I have also studied under the most favour- 

 able circumstances the movements of the otter, sea-bear, seal, walrus, porpoise, 

 turtle, triton, crocodile, frog, lepidosiren, proteus, axolotl, and the several 

 orders of fishes. 



