The sharp-eyed searcher after fossils detects these protruding, often broken and weather-worn, petrified bones, which themselves betray the presence often of other parts of their skeletons still concealed in the chalky hillside. Fortunate is he if he has discovered a specimen soon after it appeared at the surface, before the rains have washed away and destroyed most of the remains that had been there preserved. Still more fortunate is he if all or nearly all of the original skeleton has been preserved together in its natural relations. After days, perhaps weeks, of labor, the specimen is secured and shipped to the laboratory. Those parts which have been washed out of the chalky rock before the discovery of the specimen are always more or less injured and for the most part lost, their fragments strewn down the hillside, for erosion is always slow and many years may have elapsed since first the specimen had appeared at the surface. More frequently, perhaps, a few strokes of the pick and shovel disclose but one, two, or three bones remaining in the rocks. The specimen, if large, or composed of many bones, is carefully uncovered sufficiently to show its extent, and then, so far as possible, removed in large blocks of the rock. The bones themselves, notwithstanding their petrifaction, are usually soft and easily broken, and their separate removal from the matrix may require weeks or even months of labor, work which cannot be done prudently in the field. Of many specimens the rock matrix is so hard that the task of removing it from the bones is slow and difficult, indeed well-nigh impossible, for the bones are usually softer than their surrounding matrix. On the other hand, the matrix may be so soft and friable that it cannot be quarried out in blocks. In such cases the separate divisions, as large as they can be excavated and safely handled, are carefully covered with thick bandages of burlap and plaster-of-paris, often strengthened with rods of iron or boards. The skeleton of a single animal treated in this way may require weeks and even months to collect, prepare, and mount in the museum.