Vol. XVII. August, /pop. No. 



BIOLOGICAL BULLETIN 



A CASE OF NORMAL IDENTICAL QUADRUPLETS 



IN THE NINE-BANDED ARMADILLO, AND 



ITS BEARING ON THE PROBLEMS OF 



IDENTICAL TWINS AND OF 



SEX DETERMINATION. 1 



H. H. NEWMAN ANTD J. THOS. PATTERSON. 



In a former contribution from this laboratory by A. M. Spurgin, 

 M.D., occurs the following statement : " A year ago, Dr. \V. M. 

 Wheeler, of the School of Zoology, had the good fortune to 

 secure four embryos of the Dasypns novemcinctus from an adult 

 female which had been kept in the laboratory for several weeks. 

 . . . He found four placentas inclosed in one amnion, but has not 

 since had time to study the subject further." 



When the writers arrived in Austin last September they made 

 arrangements to obtain material with which further to investigate 

 this suggestive problem, and were fortunate enough to enlist the 

 services of a naturalist living in a part of Texas where the arma- 

 dillo abounds. In this way we have been able to secure several 

 gravid females, from a study of which a number of interesting 

 facts have been brought to light. 



There are always four embryos, corresponding in number to 

 the two pairs of mammae, which are thoracic and abdominal in 

 position. The embryos are not enclosed in one amnion, but each 

 has its own distinct amniotic envelope, the cavity of which does 

 not communicate with those of the adjacent amnia. This was 

 proved by the experiment of inflating one amnion and noting that 

 the air did not pass to the cavities of the contiguous amnia. The 

 four amnia, however, are enclosed in a single chorionic vesicle. 



'Contribution from the Zoological Laboratory of the University of Texas, No. 98. 

 2 American Jottrttal of Anatomy, Vol. III., No. I. 



