This decrease in the difference is unusual and indicates some error. This idea seems to be confirmed in the following way: In order to obtain the numbers of the next (second) column it is necessary to add three times the former difference, thus: 10 2 4 0 3 0 12 0 -- -- -- -- 13 2 16 0 Second column, Plate 71. If the increased difference, 2, 0, 8, 0, were retained after its appearance the result would be as follows: 7 1 10 0 Fifth column, Plate 71. 2 0 8 0 -- -- -- -- 9 2 0 0 Fourth column, Plate 71. 2 0 8 0 -- -- -- -- 11 2 8 0 Third column, Plate 71. 2 0 8 0 -- -- -- -- 13 2 16 0 Second column, Plate 71. 2 0 8 0 -- -- -- -- 15 3 6 0 First column, Plate 71. Adding the difference, 2, 0, 8, 0, to the third column, Plate 71, thus: 10 2 4 0 2 0 8 0 -- -- -- -- 12 2 12 0 we obtain the red numerals inserted in the third column. It is probable that the original or some subsequent scribe, observing an error at this point, inserted these figures as a correction. If so, he failed to remedy the confusion apparent in this portion of the series. The sum of the entire series is 303 years (360 days each) and six months, equal to 420 cycles of 260 days. I am strongly inclined to believe that this section and also pages 24 and 59 are interpolations by some aboriginal artist of a mathematical turn and advanced ability in this direction, who has given these high series more as curiosities than with reference to any specific dates or periods of time. [Illustration: FIG. 371. Specimens of ornamental loops from page 72, Dresden Codex.] Commencing in the sixth column of Plate 71_a_ and running through 72_a_ to the second column of 73_a_, is a numeral series which presents some peculiarities that baffle all attempts at explanation. Contrary to the rule which prevails in these pages it ascends from left to right and has no day symbols connected with it. In addition to this, the numbers of its lowest line are inclosed in loops of the form here shown (Fig. 371) and have no apparent connection with the other lines of the series, but, on the contrary, if taken from right to left, they present in the order usually given the numbers of the ahaues or katunes.[337-1] It is as follows: 1 1 1 1 1 1 1 2 5 8 10 13 16 0 3 6 9 11 14 17 II. 14 8 2 16 10 4 18 12 6 0 14 7(?) 2 XIV ⑪ ⑬ ② ④ ⑥ ⑧ ⑩ ⑫ ① ③ ⑤ ⑦ ⑨