30 



THE BIOLOGY OF TWINS 



to secure the earliest cleavage stages of the normally 

 developing egg, but a study of parthenogenetic cleavage,^ 

 as it occurs in atretic follicles, has been made; these 

 data undoubtedly foreshadow some of the most funda- 

 mental events of normal cleavage. Until a study of 

 normal cleavage is forthcoming the facts of partheno- 

 genetic cleavage may be accepted as a temporary 

 substitute. 



Fig. 3. — Uterus, ovaries, etc., of adult Dasypus novemcindus (arma- 

 dillo), showing simple squarish uterus with sharp fundus end (fu), 

 cervix (c), Fallopian tube (ft), ovaries (0), only one of which, the left, 

 has a corpus luteum (cl). (From Newman and Patterson.) 



THE FEMALE GENITALIA 



The uterus of the armadillo is simple and quite 

 Hke that of man and of other primates which produce 

 but one offspring at a birth. Viewed from the dorsal 

 aspect, the non-pregnant uterus appears to be broadly 

 kite-shaped (Fig. 3), with the posterior angle blending 

 into the vagina and with the right and left corners 

 connecting with the Fallopian tubes. The free or fundus 



»H. H. Newman, Biological Bulletin, XXV, No. i (1913)- 



