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BUEEAU OF AMERICAN ETHNOLOGY 



fBULL. 52 



early period. We find the plano-convex knife blade (pi. 14), the 

 spikelike plano-convex point (figs. 25, 32), the symmetric doubly 

 convex leaf-blade (figs. 24, 28), the duck-bill scraper (figs. 26, 29), and 

 the chipping hammers in both groups. The use of the fracturing and 

 the pressure implement in the shaping work was apparently common 

 to both. The specialized arrowhead is found in the quartzite group 



Fig. 41. Series of jasper leaf forms representing successive steps in the specialization of arrow points. 



(i actual size.) San Bias. 



only and in that but rarely. The anvil-stone can not be shown to be 

 characteristic of either of the groups exclusively, although it certainl}^ 

 pertains in large measure to the pebble group, while the chipped 

 pebbles are necessarily confined to the shore-pebble group. Fuller 

 collections might show even still closer correspondence between the 

 two groups. The differences do not seem so radical as to preclude 

 the idea that a single people or closely related groups of people were 

 responsible for all the chipped-stone work of these more northeastern 

 coastal sites. This likelihood is considerably strengthened by the 

 fact that differences in kind and form of material im- 

 pose distinctions in the processes and in the things 

 made. 



Comparing the whole work of the northern groups 

 with that south of Bahia Blanca, it is seen that cer- 

 tain culture differences are quite marked. The prev- 

 alence of leaf-blade forms (fig. 41) and leaf-blade 

 implements, variously specialized arrowheads and 

 spearheads (pi. 13), and drill points (fig. 42), contrasts 

 with the absence or decided rarity of these forms in 

 the north. The rarity of the plano-convex knife blade (pi. 14) in the 

 Rio Negro District (although it is common in southern Patagonia) is a 

 noteworthy fact. The duck-bill scraper occurs much less frequently 

 here than in the quartzite group of the north. The shaping processes 

 are the same throughout, although the use of the anvil-stone was 

 apparently exceptional in the south, being there devoted to the 

 fracturing of pebbles and hence confined to the pebble-yielding areas. 



Fig. 42. Drill-point 

 of jasper. ( i ac- 

 tual size.) San 

 Bias. 



