370 H. H. Newman and J. T. Patterson. 



the other. Reference to fig. 1 will show that the amnion of embryo 

 II, especially after the amnia have increased considerably in 

 size, might readily overlap the line D-V, so its embryo would 

 occupy the dorsal amniotic quadrant. The same shifting might 

 equally well occur on the ventral side. Such shiftings might take 

 place however without affecting in any way the point of the em- 

 bryonic attachment, which is immediately adjacent to the origi- 

 nal amniotic attachment (fig. 1, a. a.). Such departures from the 

 typical arrangement of embryos in the vesicle are rather rare, 

 and are not to be considered as of prime importance, for they 

 in no way affect the pairing of embryos, a relationship depending 

 on the point of attachment of the latter which is equivalent to 

 their point of origin. The significance of this arrangement is 

 discussed in a subsequent chapter. 



C. Sex of Embryos 



In thirty-eight embryonic vesicles the foetuses are sufficiently 

 advanced to permit of the accurate determination of their sex. 

 There is no exception to the rule that all embryos in a vesicle are 

 of the same sex. 



Although the armadillo hunters claim that males are consider- 

 ably more numerous than females we find no inequality of sexes 

 in the sets of embryos in our collection, exactly half of which are 

 male and half female. In the small collection of nine advanced 

 sets of mulita embryos Fernandez found that six were female and 

 three male. On this basis he proceeds to discuss the significance 

 of the apparent disproportion of sexes in the species. No doubt 

 a larger collection of embryonic sets would have shown no such 

 disproportion, for in our earlier survey of the subject of sex dis- 

 tribution we found a much larger proportion of males. 



