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220 of his cage, precisely as a basket-maker would have done. In the intervals he placed his litter, his carrots, his apples, his all, fashioning each with his teeth, so as to fit them to the spaces to be filled. To stop the interstices, he covered the whole with snow, which froze in the night, and in the morning it was found that he had thus built a wall which occupied two-thirds of the doorway."

Among the Insectivora we found a Family of animals clad in a coat of spiny armour. We are now to consider another group similarly furnished, but in which this defensive array of spines is much more strongly developed than in the Hedgehogs. The Porcupines are covered with a close series of hollow tubes, somewhat like the quills of feathers, usually terminating in a fine point of enamel, of great hardness, but in some in- stances open at the extremity, as if they had been cut off in their greatest thickness. "The spiny quills of the Porcupine," observes Mr. Martin, "consist of a smooth glossy envelope of horn, and an inner pith, or medullary substance, of a soft texture, and of a pure white. They grow from a bulbous root, formed within a cell below the cutis &#91;or true skin&#93;, and containing also a portion of fat, in which the vessels supplying its pulp and capsule are imbedded. The capsules consist of two membranes, of which the innermost secretes