The burrows, from four to five inches in diameter, are usually located on flat or gently sloping ground. They descend abruptly from eight to sixteen feet, then turn at a sharp angle and extend ten to twenty-five feet in a horizontal or slightly upward course. The tunnel at the end of the steep descending shaft is always more or less irregular in course, and branches in various directions, the branches often ending, in a rounded nest or storage chamber, but sometimes forming a loop back to the main passageway. Not infrequently two entrances some distance apart lead to these deep workings. A little niche is ingeniously dug on one side of the steep entrance shaft, four to six feet below the surface, to which on the approach of danger the owner retires to listen and determine whether it may or may not be necessary to seek safety in the depth of the den. It is from these vantage points that the resentful voices of the habitants come to an intruder in a prairie-dog “town” as he passes. The black-tailed prairie-dog, which is so numerous on the Great Plains, surrounds the entrance to its burrow with a crater-shaped pyramid of soil varying from a few inches to nearly two feet in height and serving perfectly as a dike to keep out the water. The owners keep the funnel-shaped inner slopes of the rims about the entrances in good condition by setting briskly to work to reshape them at the end of a rain-storm, digging and pushing the earth in place with their feet and molding it into a more compact mass by pressing it in with their blunt noses. The white-tailed prairie-dogs pile the dirt from their excavations out on one side of the entrance, as in the case of most other burrowing animals. Sometimes the dirt in these piles amounts to from ten to twenty bushels, thus indicating extended underground workings. The vivacity and hearty enjoyment of life by the occupants of a prairie-dog “town” is most entertaining to an observer. With the first peep of the sun above the horizon they are out on the mounds at the entrances of their burrows, first sitting erect on their hind feet and looking sharply about for any prowling enemy. If all is well they begin to run about from one hole to another, as though to pass the compliments of the day, and scatter through the adjacent grassy feeding ground.