366 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
extent of variability present in the species. Consequently 508 indi- 
viduals were taken at random and their scale or scute number counted. 
It was found that the total number of scutes in the nine bands ranged 
from 517 to 625 and that the commonest number was about 557. In 
order to get a definite idea of the distribution of the different types, 
eer 
WOOF 
100¢ 
Ce 
80+ 
10¢ 
60+ 
sof 
40 
30F 
‘ 
‘ 
517-5244 \, 
525 -5324 
533 -540, 
$41 -548 
549-556 
557-564 
565-572 
573 -580 
581-588 
589 -596 
605-612 
613— 620} 
621-625 
Fic. 62.—Polygon of variation for the total number of scutes in the nine 
bands of the armadillo (Dasypus novemcinctus), as determined by the seriation of 
508 individuals. Class range=8 scutes. The solid line represents the observa- 
tional, and the broken line the theoretical, normal curve. The abscissae refer to 
the number of scutes, and the ordinates to the number of individuals. (From 
Newman.) 
they were arranged in a variation polygon as shown in Figure 62. On 
the abscissa are arranged groups including individuals between 517 
and 524 scutes inclusive, those between 525 and 532, those between 
533 and 540, on up to a group of those from 621 to 625. All of these 
except the last included a small class with a range of 8 scutes. This 
arranging in classes was essential, for without it there would have been 
