Radiocarbon Dating of Mollusk Shells: A Reply.

grassland and not going anywhere are no longer cowpaths. The photograph shows the currently used paths in the grassland bowed toward the lower left by encroaching shrubs while faint scars above reveal where the paths once passed. In the grassland these old paths are obliterated by grass; in the shrub zone they remain bare and become broader. The great broad white zones of bare ground both inside and outside the shrubs are curved (not "rectilinear") and can scarcely be explained except as inhibition. Since severe inhibition 6 to 9 m distant from the shrubs is commonplace, with or without transverse cowpaths, it is impossible to ascribe the phenomenon to characteristically narrow cowpaths. Wells overlooked the fact that we did not credit White-crowned Sparrows (Zonotrichia leucophrys) and Goldencrowned Sparrows (Z. atricapilla) with contributing to the vegetational patterning. This they do in perceptible degree, but never do they produce a bare area unaided by initial biochemical inhibition. Their contribution consists of grazing more heavily near shrubs for a brief period after initial germination and results in a slight intensification of the patterning. Steps are being taken to preserve an area of the more instructive patterning. We are desirous of showing this to anyone who will look. C. H. MULLER W. H. MULLER Department of Biological Sciences, University of California, Santa Barbara