Although the eyes are complete in the sense that eyeballs and lenses are present, they are so small and so completely surrounded by fur that it does not appear that the Mole can get any great advantage from their possession, even when he is above ground. The diameter of the eyeball is one millimetre—that is, considerably less than the head of a "short white" pin!

At the end of the last century, my friend Mr. Lionel E. Adams set himself the task of providing some more reliable information as to the life-story and habits of the Mole, and in four years of research did not hesitate in the interests of science to break in upon the digger's privacy in order to explore his so-called "fortress," and the nursery of Mrs. Mole. He was not content with cutting sections of two or three of these erections; he examined three hundred of them, finding a considerable variation in their arrangements, but not one of them was like the familiar drawings in the books of Thomas Bell and J. G. Wood, copied from French authors.

Mr. Adams experienced great difficulty in making these observations owing to the nature of the subject, but he persevered and made plans of sections from a hundred of the three hundred hills he explored, and found that no two plans were alike. Some were very simple, others exceedingly complicated, "but," he says, "in no case have I found one to tally exactly with the time-honoured figure originating from Geoffroy Saint-Hilaire, elaborated by Blasius, and copied from him by every succeeding writer, apparently without the slightest attempt at verification."

But even in those cases where there is some approach to the plan of the old diagram, Mr. Adams found that it was clearly not due to any scheme for constructing a baffling system of bolt-runs for defensive purposes, but purely incidental to the work of excavating the nest cavity and getting rid of the material dug out. The easiest way to dispose of this redundant earth is to push it to the surface, and to do this a tunnel has to be made above the nest cavity. This, as a rule, is originally only from two to six inches below the surface, but the hoisting out of the surplus earth causes the formation of a solid dome of considerable thickness above it. The tunnels thus made to get rid of earth usually end in blind terminals, and would not be available for escape in the case, say, of the "fortress" being entered by a Weasel. It is notable that in the only one of Mr. Adams' plans that approaches nearly to the old figure there is no connection between the "galleries" and the nest cavity.

In some soils (like the Bunter Sandstone) Adams found that stones of four ounces are turned out—that is, equal to the average weight of an adult Mole. He also found that "the softer the soil, as a rule, the nearer are the runs to the surface."

In his work "De la Taupe," de Vaux says: "The Mole places his habitation in the most favourable spot in his cantonment; he studies everything, and never does he make a mistake except under circumstances which he has been unable to foresee, such as continuance of rains, a flood; then he makes up his mind promptly, and establishes himself elsewhere. It is by preference that he places his fortress in the foundation of a wall, under a hedge, at the foot of a tree."

[Pl. 6.]][C 18.
Mole making a new burrow.
When alarmed above ground it dives rapidly into soft earth.

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