The reader will remember that in the preceding description of the Heart-urchin it was mentioned that many of the spines are shaped at their ends something like spoons, and that their comparatively wide blades are used in scraping the sand and shovelling it aside. In fact, these flattened spines are natural spades, used on the same principle as the modern spade of civilisation. On the right hand of the illustration are shown two forms of spade, the one being the ordinary garden tool, and the other a rather curious implement which is in great use among the metal mines of Cornwall. The use of the ordinary spade is too familiar to need explanation, and we come to the Miner’s spade. This implement is used rather as a shovel than as a spade, the peculiar bend near the blade preventing the foot from being used as a means of forcing the instrument into the ground. In fact, it is not meant for the same office as that which pertains to the ordinary spade, neither can it be handled in the same way. [Illustration: FOOT OF AARD-VARK. FOOT OF MOLE-CRICKET. SPADES. FOOT OF MOLE.] In Devonshire there is a kind of spade in general use very much resembling the mining spade, but having a very long handle without any crutch at the end. The natural consequence of this shape is, that the spade cannot be used in the ordinary way, neither can it penetrate the earth to any depth. It can “peel” the ground, so to speak, and can cut away successive layers of soil. But as for digging “two spits deep,” or even one spit, the spade would be absolutely incapable of such a task, no matter how strong might be the hands that wield it. As for the foot, it may be put out of the question. * * * * * WE will now turn to a few examples of spades in the world of Nature. The lowest figure represents the fore-paw of the Mole, with its powerful armature of strong and sharp claws, and its broad blade of a palm. The reader will easily see that in this animal the digging powers are wonderfully developed. The peculiar form of the fore-foot closely resembles that of the miner’s spade, while the curvature of the palm serves, almost without exertion, to throw out the earth which has been scooped away by the sharp claws. To watch a Mole burrow is really a curious sight, the only drawback being that the animal sinks itself so rapidly beneath the earth that a long inspection is impossible. I have kept several moles for the purpose of watching their habits, and have always been interested in their mode of burrowing. I can only define it by using the word “scrabbling.” The animal scurries and hurries about, seeking for a tolerably soft piece of ground. When it has found one, it travels no further, but scratches away with its fore-paws with wonderful power and rapidity, seeming to sink, as it were, into the earth, rather than to excavate a tunnel. * * * * *