This file was derived from scanned images. With the exception of two typographical errors that were corrected, the original text and copies of the included illustrations are presented. The smaller graphic shown as Figure 2 was processed to remove moire effects when viewed at smaller sizes. Clicking on the Figures will allow the user to view a copy of the original scanned image from which it was derived.

Typographical Errors Corrected:

   Page 589, Paragraph 2: Tepalcatapec => Tepalcatepec

   Page 592, Paragraph 2: ground color => ground-color

In the original, Figure 1 had the notation X5 after the caption to let the reader know that the image was enlarged by a factor of five. As the illustration in the HTML page will display at different sizes based on the resolution of the monitor and the size the browser window, it was decided to remove that notation and the viewer would derive the measurements from the body of the paper.