Page:Popular Science Monthly Volume 62.djvu/533

Rh practically one of swallowing air. When it becomes necessary for the hellbender to take in a fresh supply of air, it swims towards the surface of the water until the tip of the snout is exposed; then, by swelling downward the skin of the floor of the mouth, a huge mouthful of air is drawn in, and the animal, now arching upward its neck and back, slowly sinks to the bottom, the swallowed air passing back to the lungs either by its own buoyancy, the lungs now being higher than the throat, or by a sort of peristaltic action of the throat. As the animal sinks, a considerable portion of the air that was taken into the mouth escapes through the nostrils or through the gill openings. After reaching the bottom, the animal frequently retains, for some time, the strongly arched position, as though the region of the lungs were buoyed up by the air that had just been taken in. The air is gotten rid of partly by a quick expiration when the animal comes to the surface, and partly by an occasional bubble sent up from the bottom. If the animal be alarmed as by a sudden approach to the tank in which it is contained, it frequently sets free one or more large bubbles of air, perhaps by the involuntary relaxation of certain muscles, perhaps by a voluntary expulsion of superfluous air, to enable it better to escape the supposed danger. The length of time that the hellbender remains under water seems, in captivity at least, to be quite variable. I made a series of observations on three individuals, a very large one, a very small one and a medium-sized one, and the average interval between inspirations was about fifteen minutes. The longest time that any individual was actually observed to remain below the surface was forty-three minutes. In motion the hellbender is usually slow and awkward. On a smooth dry surface, as the top of a table, it is almost helpless, because the slime secreted by the skin soon dries and becomes so sticky as almost to prevent motion. Even in its native element its motions are usually awkward, though when swimming rapidly this is not apparent. In crawling over the bottom, the diagonally opposite legs very nearly 'keep step,' i. e., the left front leg and the right hind leg move forward at the same time. In active swimming the tail is the most effective organ, as in the alligators. If an individual, which is lying quietly on the bottom, be watched carefully it will frequently be noticed that it has a slight rocking or swaying motion, caused by the alternate straightening or relaxing of the legs, similar, perhaps, to the swaying motion of elephants. In captivity they usually congregate in the darkest portions of their tank, crawling under boards or stones if these be present, or under each other if there be no better hiding place. If not lifted above the surface of the water, they may be handled with scarcely a struggle, but if taken from the water they struggle to regain their native element. As a rule the smaller specimens were more active than the larger.