The North American Wolf, which extends from Greenland in the north to Mexico in the south, is often separately considered as _Canis occidentalis_. It differs from the European kind chiefly in its fur being finer, denser, and longer, and in the curious fact that its feet are, as Sir John Richardson remarks, very broad, so as to enable it to run easily on the snow. The development of these natural snow-shoes in the American Wolf fitting it so beautifully for its particular mode of life is highly interesting. This species is entirely absent from South America, but its wide distribution in North America may be gathered from Richardson’s account:-- “Wolves are found in greater or less abundance in different districts, but they may be said to be very common throughout the northern regions; their footmarks may be seen by the side of every stream, and a traveller can rarely pass a night in these wilds without hearing them howling around him. They are very numerous on the sandy plains which, lying to the eastward of the Rocky Mountains, extend from the sources of the Peace and Saskatchewan Rivers towards the Missouri. There bands of them hang on the skirts of the Buffalo herds, and prey upon the sick and straggling Calves. They do not, under ordinary circumstances, venture to attack the full-grown animal; for the hunters informed me that they often see Wolves walking through a herd of Bulls without exciting the least alarm; and the marksmen, when they crawl towards a Buffalo for the purpose of shooting it, occasionally wear a cap with two ears, in imitation of the head of a Wolf, knowing from experience that they will be suffered to approach nearer in that guise.”[126] The American Wolf extends into Greenland, where the Eskimo take it in traps of a very novel construction, “made of strong slabs of ice, long and narrow, so that a Fox can with difficulty turn himself in it; but a Wolf must actually remain in the position in which he is taken. The door is a heavy portcullis of ice, sliding in two well-secured grooves of the same substance, and is kept up by a line, which, passing over the top of the trap, is carried through a hole at the farthest extremity; to the end of the line is fastened a small hoop of whalebone, and to this any kind of flesh bait is attached. From the slab which terminates the trap a projection of ice, or a peg of wood or bone, points inwards near the bottom, and under this the hoop is lightly hooked; the slightest pull at the bait liberates it, the door falls in an instant, and the Wolf is speared where he lies.”