same as that used to shape or reduce a stone to a desired rough form preparatory to grinding as a finishing technique. It was discovered in our own experience in the manufacturing of stone artifacts (Treganza and Valdivia, 1955) that when a core hammerstone lost its sharp edges through battering it was of little use, and continued use of such a blunt hammerstone often broke the object being manufactured. Where this pecking technique is used to sharpen manos and metates three end products result in terms of exhausted tools and become part of the camp refuse. Hammerstones occur as subangular nodules with battered blunt edges; manos, when they are worn too thin, usually break in the process of pitting, and the metate in time wears through or the bottom gets knocked out resulting in a "killed" artifact. What has earlier been referred to by many authors as the "ceremonial killing" of an artifact might also be viewed as the end product of function. It is noted that Phase II site LAn-2 shows a sudden decline in core tools accompanied by a decline in manos and metates. Presumably the mortar becomes a replacement. Recovered from approximately one-tenth of the Tank Site were 2,556 manos, 329 metates, both whole and broken, and 1,478 worn-out hammerstones. No clear breaking point could be established between an unused scraper plane, which is really a core with one or more flat bottoms, and a partly used hammerstone, or between just a plain core and a partly used hammerstone. Probably most of our scraper planes might be considered potential hammerstones. This being the case, the scraper plane may be just a "myth artifact" growing out of the literature and typologies rather than being an existing reality. This does not imply that all so-called core and flake tools or even some scraper planes should be considered in the same light. It merely points up the fact that Western terminology and typology might be reëxamined. One exception might be considered in the Type IA scraper planes (Treganza and Malamud, 1950, pl. 17, _a_), which, because of symmetry, flat base, marginal and all-over surface flaking, are similar to the classical forms of the San Dieguito Culture.