2. Specimen made from a thin piece of banded, laminated chert. Shaping was done merely by marginal flaking, as the original surface shows no working. Coming from a depth of 60 inches, this marks the greatest depth of any large point. Length, 5.4 cm.; width, 2.8 cm.; and 5 cm. thick (pl. 21, _j_). 3. Basal fragment of a large blade. This broad, angular base is a unique occurrence for the Tank Site, though some parallels may be noted in Lake Mohave specimens. This single piece possesses sharp, angular shoulders that terminate in a broad, flat, angular base. The material is a white chert (pl. 21, _k_). [Illustration: Figure 5. Metate Types] GROUND OR PECKED STONE _Manos and Metates_ As heretofore, manos far outnumber metates in the deposit. An explanation of this inequitable representation of milling stones has already been discussed in some detail (Treganza and Malamud, 1950; p. 140), _viz._, that the more rapid wear of the nether stone periodically called for manos of somewhat varying shapes to conform to the changing contour of the metate throughout its serviceable life. Proof to substantiate this thesis is lacking, but it appears to be a reasonable possibility. Also, the practice of pecking manos to increase the effectiveness of their grinding surfaces must have resulted in considerable breakage, as judged by the large number of fragments. Of 2,556 manos and 329 metates, whole and fragmentary, 962 and 79 respectively, were classifiable. The descriptive categories derived from the 1947 data proved adequate in defining the limits of variability and patterning displayed by our recent acquisitions. Some pieces exhibit technological refinement of types earlier described. _Metates_ Metates are of three types, called here deep basin, shallow basin, and flat slab. As was true last season, the material is predominantly sandstone for all three forms. _Type I, deep basin (fig. 5, a, c, e)._--These are the most abundant. Fifteen complete specimens and seventeen fragments were recovered. In both form and size there exists a close parallel between this type and those associated with the Oak Grove Culture of the Santa Barbara area. _Type II, shallow basin (fig. 5, b, d; pl. 18, c right)._--This type is represented by fifteen complete and eleven fragments. _Type III, slab (fig. 5, f; pl. 18, c)._--Like type II, the slab metate is less common, being known only through eleven complete and ten fragmentary specimens.