XXI 
THE BIOLOGY OF TWINS 
HE path of light is often strangely circuit- 
ous, for who would have thought that the 
study of an armadillo would illumine the problem of 
human twins? That this is so has been vividly 
shown by Mr. Horatio Hackett Newman in an 
entertaining volume entitled The Biology of Twins.’ 
One cannot help envying him the story he has 
to tell. Not uncommon in Texas is an old-fashioned 
creature, the Nine-banded Armadillo, a sort of liv- 
ing fossil belonging to a stock unique among 
mammals in having bony plates in its skin. Be- 
tween an arched cuirass over its shoulders and a 
similar shield over its loins it has nine movable 
bands of bony armor. The body is about eighteen 
inches in length, not counting the pointed armored 
head with mulish ears and the long tapering tail. 
Baskets made of armadillo carapace with the tail 
arched over to form the handle are common curios 
in the New World. The creature is mainly in- 
sectivorous, and hunts at night, retiring to its 
deep six-foot burrow during the day. Its armor 
is defensive against the thorns and spines of the 
arid vegetation amongst which it lives, and stories 
* Chicago University Press, 1917. 
158 
