TWINNING IN OTHER SPECIES OF ARMADILLO 77 



A good many cases of rudimentary embryos have 

 been found in D. novcmcinctiis, but the mortality of 

 embryos in that species is very low. 



TWINS IN EUPHRACTUS VILLOSUS^ 



Late in the year 19 15 there appeared a third paper 

 by Fernandez^ which gives important information about 

 the development of the hairy armadillo or Peludo 

 {Euphractus villosus) ? 



Euphractus possesses a mode of development strik- 

 ingly different from that of Das y pus and a new and 

 totally different kind of twinning. When one examines 

 the advanced embryonic vesicle of this species, he finds 

 a situation like that shown in Fig. 32. Usually two 

 fetuses are present within what appears to be a single 

 chorion, and they are separated from one another by a 

 membrane that appears to be made up of the fused 

 amnia of the two fetuses. Each fetus has its own 

 separate umbilicus, and the two are not fastened to the 

 wall of the vesicle with any regard to the uterine axes of 

 symimetry. Fernandez examined ten advanced vesicles 

 and found that in seven cases the twin fetuses were 

 of opposite sexes; in two cases both were female and in 

 one case both were male. The occurrence of fetuses of 

 opposite sexes seemed strange in the case of twins that 

 had every appearance of being monochorial; hence the 

 situation deserved careful investigation, 



^ This species has been incorrectly attributed by Fernandez to the 



genus Dasypus. 



^M. Fernandez, Anat. Anzcigcr, Bd. 48, No. 13/14, i9i5- 



3 The genera Euphractus and Dasypus are by some authors placed 



under one genus, and not without some show of reason, for the species 



of the two genera are certainly very similar. 



