The series of outlines presented in Fig. 14 will assist in giving a clear understanding of the forms described.
Leaf Shaped.-Sub-class A.—Thin and usually finely chipped implements of the form of a laurel leaf—elliptical, and pointed at both ends. This includes the French Solutreen type of the Paleolithic period of the Stone Age.
Sub-class B.—These may be thicker and ruder than sub-class A. Some are more oval, and the bases are not pointed, but are either straight or convex. This class includes the leaf-shaped argillite implements found by Dr. C. C. Abbott in the Delaware river gravels at Trenton, New Jersey.
Sub-class C.—Long, thin blades, with nearly straight edges, more like a dagger or poignard. The base may be either convex, straight, or concave. Many of them show traces of attachment to a handle by means of bitumen or gum. They are peculiar to the Pacific slope.
Triangular.—This class includes all forms approaching a triangle, whether the bases or edges be convex, straight, or concave. They are without stems, and, consequently, without shoulders, but in some specimens the concavity of the base produces barbs.
Stemmed.—This class includes all varieties of stems, whether straight or expanding, and all varieties of bases or edges, whether convex, straight, or concave.
Sub-class A.—Lozenge-shaped, rude, and indefinite stems.
Sub-class B.—Shouldered, but not barbed at the shoulder. In occasional specimens barbs are produced at the base, but only by its concavity and width.
Sub-class C.—Shouldered and barbed.
Nearly all of the convex bases are smooth, as though worn. The purpose of this is unknown.
Peculiar Forms.-These have such peculiarities as to distinguish them from other classes, but are restricted in number and locality.
Sub-class A.—Beveled edges; the bevel is almost always in one direction.
Sub-class B.—Serrated edges.
Sub-class C.—Bifurcated stems.
Sub-class D.—Extremely long barbs, usually square at the ends.
Sub-class E.—Triangular in section.
Sub-class F.—Broadest at the cutting end-trenchant transversal.
Sub-class G.—All those made of slate and polished.
Parts of stone arrow and spear heads or knives are: Point, base, side, edge, shoulder, barb.