192 PICTURE-WRITING OF THE AMERICAN INDIANS, 
Sixth type. Concentric rings without a central cup.—In many cases the concentric 
rings of the types already described appear without a central cup or depression, 
which is most frequently wanting in the complete concentric circles of the third 
type. 
Fie. 149.—Cup sculptures at Auchnabreach, Scotland. 
Seventh type. Concentric circular lines of the form of a spiral or volute.—The central 
beginning of the spiral line is usually, but not always, marked by a cup-like exca- 
vation. 
