MCGEE] THE CENTRIPETAL STROKE 237* 



worn and polished like the ftice, though to a less degree. The speci- 

 men was found at a recently occupied Jacal, midway between Puuta 

 Antigualla and Puuta Ygnacio; it lay in the position of use, though 

 half concealed by a cholla thrown over it, with the hupf shown in jdate 

 LVi; it was soaked with fat and smeared with the debris and intestinal 

 contents of a turtle, as partly shown in the illustration. 



The largest ahst seen in SeriUuid is illustrated in plates xxxix and 

 XL, on a scale of one-third linear (its maximum length being 15| 

 inches = 395 cm.); it is a dark, finegrained silicious schist or quartzite, 

 quite obscurely laminated; it weighs 3.'{ pounds 8 ounces (15.20 kilo- 

 grams). It is a natural slab, probably washed from a talus and slightly 

 wave- worn; it might have come originally from either the southwestern 

 flanks of Sierra Seii or the more southerly half of Sierra Kunkaak — 

 certainly hundreds of similar slabs strew the eastern shore of liahia 

 Kunkaak, while the western shore, esiiecially about Punta Narragau- 

 sett, would yield thousands. Its artificial features (aside from miscel- 

 laneous battering) are limited to grinding of the two faces defined by 

 structure planes. The principal face is abraded into an oblong or 

 si)Oon-shape basin, about 8 inches (20 cm.) long, 5 inches (10 cm.) broad, 

 and full}' three fourths of an inch (2 cm.) deep, the basin penetrating 

 two or three lamina' of the slab in such wise as to ])roduce the annular 

 markings faintly shown in plate xxxix; the obverse is slightly rubbed 

 aud giound and somewhat battered, like the face of the preceding 

 specimen; and both sides are flecked with a fine but dark flour-like 

 substance (doubtless derived from grinding mesquite beans, etc) forced 

 into the texture of the stone by the grinding process. The entire slab 

 is greasy and blood-stained, while battered spots about the edges aud 

 angles of tlie jirincipal face record considerable use as an anvil for 

 breaking up (piarry — indeed, shreds of turtle flesh and bits of intes- 

 tinal debris still lodge in some of the interstices. The specimen was 

 taken from the old ranclieria at the base of Punta Tormenta, where it 

 had apparently been in desultory use for generations. 



A sort of connecting link between ahst and hupf is afforded by elon- 

 gate beach pebbles, such as that illustrated in plate XLI, which lay 

 beside the large ahst last described, and which bears a few ini'onspicu- 

 ous marks of use in slight battering at both ends, with a few shreds of 

 turtle flesh about the blunter extremity (at the right on the plate). 

 The specimen is shown natural size; it is of pinkish gray trachyte (?), 

 and weighs 1 jiound 12 ounces (0.79 kilograms). It is noteworthy 

 chiefly as an illustration of the Seri mode of seizing and using hand- 

 implements (a mode repeatedly observed at Costa Kica in 1894); the 

 pebble comfortably fits the Caucasian hand, held hammerwise; it is 

 intuitively grasped in this way, and when so seized and used with an 

 outward swing forms an effective implement for bone-crushing, etc, the 

 natural striking-point being near the free end; but the centripetally 

 moving Seri invariably seizes the specimen in such manner that the 



