The simplest form of rock inscription is almost ubiquitous. In Europe, Asia, Africa, America, and Oceanica, shallow, round, cup-like depressions are found, sometimes in rows, sometimes singly, sometimes surrounded by a ring or rings, but often quite plain. The cup-markers often arranged their sculpturings in regularly spaced rows, not infrequently surrounding them with one or more clearly cut rings; sometimes, again, they associated them with concentric circles or spirals. Occasionally the sculptors demonstrated the artificial character of their work by carving it in spots beyond the reach of atmospheric influences, such as the interiors of stone cists or of dwellings. It must, however, be noted that, although there is thus established a distinction between those markings which are natural and those which are artificial, it is possible that there may have been some distant connection between the two, and that the depressions worn by wind and rain may have suggested the idea of the devices, now called cup-markings, to those who first sculptured them. Vast numbers of these cup stones are found in the British islands, often connected with other petroglyphs. In the county of Northumberland alone there are 53 stones charged with 350 sculptures, among which are many cup depressions. So also in Germany, France, Denmark, and indeed everywhere in Europe, but these forms took their greatest development in India. The leading work relating to this kind of sculpture is that of Prof. J. Y. Simpson (_a_), afterward known as Sir James Simpson, who reduces the forms of the cup sculptures to seven elementary types, here reproduced in Fig. 147. His classification is as follows: [Illustration: FIG. 147.--Types of cup sculptures.] First type. _Single cups._--They are the simplest type of these ancient stone-cuttings. Their diameter varies from 1 inch to 3 inches and more, while they are often only half an inch deep, but rarely deeper than an inch or an inch and a half. They commonly appear in different sizes on the same stone or rock, and although they sometimes form the only sculptures on a surface they are more frequently associated with figures of a different character. They are in general scattered without order over the surface, but occasionally four or five or more of them are placed in more or less regular groups, exhibiting a constellation-like arrangement. Second type. _Cups surrounded by a single ring._--The incised rings are usually much shallower than the cups and mostly surround cups of comparatively large size. The ring is either complete or broken, and in the latter case it is often traversed by a radial groove which runs from the central cup through and even beyond the ring. Third type. _Cups surrounded by a series of concentric complete rings._--In this complete annular form the central cup is generally more deeply cut than the surrounding rings, but not always.