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NATIONAL GEOGRAPHIC SOCIETY, TECHNICAL PAPERS 
FIGURE 1—FRONT OF STELA “C” SHOWING a TIGER MASK” PANEL; ALTAR STONE 
IN FOREGROUND 
AN INITIAL SERIES FROM TRES ZAPOTES 
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FIGURE 2-BACK OF STELA a C” SHOWING DOT AND BAR DATE; 
ALTAR STONE TO THE LEFT 
posure, but which is still visible. The bars 
are 12 cm. in length and 1.5 cm. in width. 
The bar forming the numeral 6 of the tun 
coefficient is somewhat thicker than the 
others, being 2 cm. across. This was prob¬ 
ably done intentionally for esthetic rea¬ 
sons, as it is the only single bar in the 
column and being wider tends to give bet¬ 
ter balance to the design. The dots are 
not separated from the bars by equal inter¬ 
vals, that of the tun coefficient being sepa¬ 
rated from its bar only by the width of 
the groove. The spaces separating the 
numerals, however, are identical and ap¬ 
pear to have been measured. The circular 
grooves around the dots are likewise identi¬ 
cal and were evidently made with the same 
tubular drill. The operator of the drill 
apparently bore down more heavily on the 
left side, as in almost every instance the 
grooves around the dots are deeper on this 
side and in some instances are not visible 
at all on the right side. The incised lines 
forming the designs of the two glyphs are 
rather lightly drawn and create a less rigid 
effect than the numerals. 
Although the projecting parts of one or 
two of the dots have been knocked off, all 
of the numerical elements are clear and un¬ 
mistakable at first glance excepting for the 
dot above the three bars of the katun co¬ 
efficient. The middle part of the upper 
bar of the katun coefficient is broken, evi¬ 
dently by a heavy blow used in breaking 
the original monument, and the dot directly 
above is badly defaced, probably from the 
same cause. Careful study, however, re¬ 
moves all reasonable doubt of the existence 
of this dot. Almost all of the semi-circular 
lefthand side of the groove outlining the 
dot still remains (figure 6), and enough of 
the raised surface projects to cast a shadow 
when the light strikes it at an angle (fig¬ 
ure 5). In addition to being exactly cen¬ 
tered and properly spaced above the bar, 
the diameter of the portion of groove re¬ 
maining is absolutely identical with the 
grooves surrounding the other dots. When 
freshly unearthed this groove was rendered 
perfectly conspicuous by the yellow in¬ 
crustation previously mentioned. Further¬ 
more, assuming that the baktun and katun 
coefficients were spaced the same as the 
remaining numerals, if no dot existed a 
corner of the baktun bar would appear in 
the undefaced area above the lefthand 
upper bar of the katun numeral. 
Assuming then that the number 6 ad- 
