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Page:Popular Science Monthly Volume 34.djvu/48

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38
THE POPULAR SCIENCE MONTHLY.

turtles and tortoises, which is fitted for grasping prey and not at all specialized for use as a shovel or digging instrument. A very slight examination of the sandy woodlands which are principally occupied by this creature will, however, convince the observer that the gopher, though selective processes have not helped him in his arduous task, is by dint of sheer strength and admirable persistency capable of doing work of singular magnitude.

The traveler in Florida may notice even from the windows of the railway-train that all over the surface of the soil in the pinewoods lie little heaps of sand which contain about one half a cubic foot of material which has been thrown upon the surface since the last period of rains. Sometimes there are only a dozen or two of these heaps to the acre, but they often amount to as many as two hundred or more in that area. Where they are few in number, we may remark that they are distributed in a tortuous line. Where they are very plenty, these tortuous lines intersect each other in such varied directions that no order in the distribution of the hillocks is discernible. Closer observation will show that these heaps are thrown out upon the burrows formed by the gophers. At first it might be supposed that they represented the points of entrance or exit of the subterranean passages, for it seems possible that the soft sand has fallen down over the opening so as to conceal its original position, and thus give the accumulation the aspect of a mere heap; but if the student takes pains to dig down into these little mounds, he will find that they do not communicate directly with the burrows. It is generally impossible to trace in the loose sand the manner in which they have been thrust up to the surface.

A little careful searching will show the way in which these curious mounds have been formed. Here and there, but rarely perhaps in one amid a hundred of these mounds, we find the place where the reptile entered the ground. This opening is at once seen to be quite separate in character from the mounds which first attract the eye. It consists of a clearly defined tunnel, the sides commonly somewhat smooth and compacted by the energy with which the body of the creature has been driven through it. The passage inclines steeply downward, descending at the outset at an angle of from 20° to 30°, then turning at the depth of two or three feet to a more horizontal position. On the surface, a little beyond this entrance, is a heap of débris, which consists of the sand taken from the passage. A few feet in from the opening, the passage appears to be closed by loose material which was not ejected from the mouth of the tunnel. Although I have been unable to catch these tortoises at work, I have succeeded by tolerably safe inferences in tracing their method of operation. When they