In his search for grass the buffalo displayed but little intelligence or power of original thought. Instead of closely following the divides between water courses where the soil was best and grass most abundant, he would not hesitate to wander away from good feeding-grounds into barren "bad lands," covered with sage-brush, where the grass was very thin and very poor. In such broken country as Montana, Wyoming, and southwestern Dakota, the herds, on reaching the best grazing grounds on the divides, would graze there day after day until increasing thirst compelled them to seek for water. Then, actuated by a common impulse, the search for a water-hole was begun in a business-like way. The leader of a herd, or "bunch," which post was usually filled by an old cow, would start off down the nearest "draw," or stream-heading, and all the rest would fall into line and follow her. From the moment this start was made there was no more feeding, save as a mouthful of grass could be snatched now and then without turning aside. In single file, in a line sometimes half a mile long and containing between one and two hundred buffaloes, the procession slowly marched down the coulée, close alongside the gully as soon as the water-course began to cut a pathway for itself. When the gully curved to right or left the leader would cross its bed and keep straight on until the narrow ditch completed its wayward curve and came back to the middle of the coulée. The trail of a herd in search of water is usually as good a piece of engineering as could be executed by the best railway surveyor, and is governed by precisely the same principles. It always follows the level of the valley, swerves around the high points, and crosses the stream repeatedly in order to avoid climbing up from the level. The same trail is used again and again by different herds until the narrow path, not over a foot in width, is gradually cut straight down into the soil to a depth of several inches, as if it had been done by a 12-inch grooving-plane. By the time the trail has been worn down to a depth of 6 or 7 inches, without having its width increased in the least, it is no longer a pleasant path to walk in, being too much like a narrow ditch. Then the buffaloes abandon it and strike out a new one alongside, which is used until it also is worn down and abandoned. To day the old buffalo trails are conspicuous among the very few classes of objects which remain as a reminder of a vanished race. The herds of cattle now follow them in single file just as the buffaloes did a few years ago, as they search for water in the same way. In some parts of the West, in certain situations, old buffalo trails exist which the wild herds wore down to a depth of 2 feet or more.