This silence was suddenly broken, as was my reverie, by a sharp ringing whistle; it was so piercing and clear, that I could not believe it was produced by an animal. Hardly had it died away, when another whistler took it up, then a third, and so on, until at least a dozen had joined in the chorus. I stole carefully in the direction from which the sound came, but as I neared the spot the whistle ceased, and it was now far too dark to descry any object on the ground. So, in doubt, and sorely puzzled to account for such an unusual sound, and with a firm determination to unravel the mystery in the morning, I returned to my camp. Could it be Indians? No, impossible; there were far too many whistlers, and the tone of each whistle was precisely alike. I was equally sure it was not the cry of the rock-whistler (_Actomys_); that sound I knew too well. What could it be? As the grey light of morning came peering into my tent, I started off to investigate the secret of the mysterious whistler; but all I could discover, after a long and diligent search, was, that there were numerous runs and burrows excavated in the sandy banks of the river, but by what sort of animal I could not for the life of me guess. Setting a steel-trap at the entrance to one of the holes, I strolled down to the Indian village, thinking I should possibly be able to find out from the redskins what it was that made such shrill sounds. Partly by signs, and by using as much of their language as I knew, I endeavoured to make the old chief comprehend my queries. After attentively watching my absurd attempts to produce a ringing whistle by placing my fingers in my mouth, and blowing through them until my face was like an apoplectic coachman’s, a smile of intelligence lit up his swarthy visage: then I violently dug imaginary holes, and explained that the sounds came about twilight; he nodded his head, dived into the tent, and disappeared in the smoke, to shortly emerge again with a rug or robe, made from the skins of an animal that was quite new to me. It was beautifully soft, glossy, and brown. The skins were about the size of a large rat’s, and about twenty in number. Here, then, was the dawn of a discovery. He called the animal _Ou-ka-la_, and made me understand that it lived on roots and vegetable matter, and burrowed holes in the ground. As the daylight faded out, I again took my seat; and, just as before, when everything was silent, the woods echoed with the Ou-ka-la’s cry. I longed for morning, and hardly waited for light, but hastened off to my trap and, joy of joys, I had one sure enough, caught by the neck. Poor Ou-ka-la! your friends had heard, and you had given, your ‘last whistle.’ He was dead and cold—trapped, perhaps, whilst I listened wonderingly, keeping my lonely vigil. A very brief examination revealed the fact that I had caught a magnificent specimen of the Aplodontia leporina, of which I had only read.