Page:Popular Science Monthly Volume 34.djvu/47

From Wikisource
Jump to: navigation, search
This page has been proofread, but needs to be validated.
37
HABITS OF THE GREAT SOUTHERN TORTOISE.
HABITS OF THE GREAT SOUTHERN TORTOISE.

By N. S. SHALER,

PROFESSOR OF PALEONTOLOGY IN HARVARD UNIVERSITY.

IN a recent paper published in "The Popular Science Monthly" for February, 1888, I called attention to the effect on the soil produced by various burrowing animals. At that time I had not seen the work done in the under-earth by the Gopherus Carolinus, the largest of our North American tortoises, a creature which, on account of its peculiar habits and the geological effects which it brings about, is worthy of an attention which it has not received. It is a well-known fact that land-tortoises are particularly abundant on the American continent. Though found elsewhere, and once extremely abundant in other lands, they are now most plentiful and of largest size in the Americas, and the Galapagos Islands, off the western coast of South America. The greater part of these creatures have the habit of spending the most of their lives on the surface of the ground, only resorting to the under-earth for occasional shelter or during the annual period of rest or hibernation. The gopher, on the other hand, has developed the habit of underground life to such a degree that it may fairly be reckoned as an essentially subterranean form. The greater of our Southern species, and the one to which I shall devote this paper, dwells for the greater part of its life below the surface, only coming occasionally from its burrows. It appears to be by far the largest species of our vertebrates which is normally subterranean in its mode of life. The region at present occupied by this species is narrowly limited; it includes, so far as I have been able to find, only the southernmost part of our Gulf States, the southern portion of South Carolina, and the seaboard region of Georgia, Alabama, and Florida. Within this considerable area it is limited to the regions of the sand-plains, for in those districts alone does it find the soil suited to its peculiar habits.

The gopher, it should be noted, is of considerable bulk, having in adult specimens a length of fifteen inches or more, a width of about twelve inches, and a thickness from the breast to back of from eight to twelve inches. At first sight of the creature, it seems as if its form was totally unfitted for underground movements. The front of the animal is very blunt, and calculated to oppose about the maximum of resistance to movements through the earth. The fore-limbs are not to any degree specialized for grappling with the earth which has to be moved to form the burrow, and the head does not differ from that of our ordinary