We have suggested cog stones in southern California may constitute the counterpart of the spindle charm stones of central California with the south boundary of the Chumash marking the near southern limit of the spindle forms. Material out of which cog stones have been made is of some interest. The Tank Site specimens range through volcanic tuff, siliceous sinter, escoriated basalt, to a fine-grained basalt. From other areas the same materials are present plus sandstone, granite, and granodiorite. Steatite, one of the most easily worked stones, appears to be absent. Obviously the hardness and type of stone were of little importance. The appearance of the finished product likewise varied. Some specimens are a product of perfection, others of the roughest sort. Perforated specimens might suggest hafting, but few are of this type. The suggestion of a ceremonial usage of cog stones is not solely lacking in evidence. In 1936-1937, under the Works Progress Administration, Mr. J. W. Winterbourne excavated two sites in Orange County known as the Banning Site and the Norris Site. The following are excerpts from a letter dated April 13, 1939, to Edwin F. Walker from J. W. Winterbourne (we are indebted to Mr. H. Eberhart for providing this data from his manuscript on cog stones): "I am enclosing some data on cog stones that one of the clerks gathered from the field notes.... We have noticed several peculiarities regarding this cogged discoidal. First, that the Banning Estate Site seems to have produced as many of these stones as all the other sites where they are found combined; second, that the stones in most cases are found in the clay completely below the camp debris; third, that rarely have they been found in association with other artifacts except the discoidal; fourth, that they seem never to have served a utilitarian purpose as they are not pitted or polished and rarely broken; fifth, if broken, in almost every case the Indians attempted to mend them with asphalt; sixth, that the material used in their manufacture is with few exceptions a vesicular basalt which is found in outcrops in the San Joaquin Hills and at various points in the Santa Ana Mountains; seventh, that the number of cogs or depressions may vary three to twenty-five or thirty-eight, that the stone may be perforated near the center of the planes or it may not be, but that usually there is a depression near the center of both obverse and reverse planes."