XXI 

 THE BIOLOGY OF TWINS 



THE 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 



1 Chicago University Press, 1917. 

 158 



