(b) Base straight. (c) Base convex. (C) Stem contracting from base—with or without barbing. (a) Base concave. (b) Base straight. (c) Base convex. II. Scrapers. Types. 1. With one or more scraping edges. 2. Without or with notch (including circular.) III. Perforators. Types differentiated by 1. Cross-section. (A) Round. (B) Quadrangular or irregular. 2. Stem. (A) Without stem. (B) With stem. (a) Stem expanding gradually. (b) Stem expanding suddenly. IV. Hammer-stones. Types. 1. Spheroidal. 2. Discoidal (a) “Pitted.” (b) Not “pitted.” 3. Elongated (a) Grooved. (b) Not grooved. _Ground Stone_ I. Problematical forms. 1. Laminæ (i. e., flat “spuds,” “gorgets,” and pendants.) Types. (A) Spade-shaped. (B) Ovate. (a) Sides concave (not common). (b) Sides straight. (c) Sides convex. (C) Leaf-shaped. (D) Spear-shaped. (E) Rectangular. (a) Sides concave. (b) Sides straight. (c) Sides convex. (F) Shield-shaped. (G) Pendants. (a) Celt-shaped. (b) Rectangular. (c) Oval or circular. 2. Resemblances to known forms. (A) Animal-shaped stones. (B) Boat-shaped stones. (C) Bar-shaped stones. (a) Longer, resembling true “bars.” (b) Shorter, “ridged” or “expanded gorgets.” (D) Spool-shaped stones. (E) Pick-shaped stones. (F) Plummet-shaped stones. (G) Geometrical forms. (a) Spheres. (b) Hemispheres. (c) Crescents. (d) Cones. 3. Perforated stones with wings. (A) Wings with constant rate of change of width. (a) Wings expanding from perforation. (b) Wings with sides parallel. (c) Wings contracting from perforation. (B) Wings with varying rate of change of width. II. Tubes and tube-shaped stones. III. Beads. IV. Pitted stones other than hammer-stones. [Illustration: FIG. 22. Indians quarrying and hammering quartzite boulders. From 15th _Annual Report_, Bureau of Ethnology. Designed by Holmes. ] [Illustration: FIG. 23. Direct percussion. Manner of striking where the edge is sharp. ] ARTICLES IN CLAY Simple vessels in clay may be presumed to cover all forms except eccentric or conventionalized (i.e., animal-shaped) forms on the one hand, and discs and pipes on the other. [Illustration: FIG. 24. (S. about 1–3.) A chipped hoe or digging-tool, and four specimens from the ancient quarries near Herndon, Tennessee. Phillips Academy collection. A complete nodule is shown in the lower right-hand corner. The others are broken nodules, showing the concretionary character of the flint. ]