136 CASA GRANDE, ARIZONA [WTH. ANN. 28 
called the straight-tube variety, which is considered by the best 
authorities to be the prehistoric form in the Southwest. 
It has been suggested that the fragment of stone shown in plate 
61, containing a cavity worked in the side, is an unfinished pipe, but 
it is so slightly shaped that its final function can not be definitely 
determined. 
Spindle whorls—The spindle whorls from Casa Grande resemble 
those of Mexico. This form of spinning whorl has never been 
recorded north of the Mogollon Mountains or on the Colorado 
Plateau, but is found southward from the Gila into Central America. 
Fic. 42. Bowl bearing bird’s head decoration (restored). 
Many of the specimens are very much worn on the edges and one is 
exceptional in being grooved on the rim (fig. 43). 
Perforated disks.—In. addition to the spindle whorls above de- 
scribed were found many perforated pottery disks, some of which 
bear ornamental designs. The character of the decoration on some 
of these shows that they are simply fragments of pottery cut into 
disk form, while in others the disks were evidently ornamented after 
they were made. Small pointed rods associated with these whorls 
are also represented in the collection. Among the finest of the per- 
forated disks are those made of slate. Several clay disks have no 
central perforation, a fact which leads the writer to ascribe to them 
uses other than those connected with the perforated variety. 
Slabs.—The writer is unable to explain the purpose of several 
fragments of clay slabs (pl. 74 and fig. 44), some bordered by a 
