141 



seems to prevail in the actual arrangement of the nipples. In nursing females 

 the distortion due to* traction may possibly upset the normal order of disposi- 

 tion, but in two nursing females examined the condition appears to be a very 

 irregular one. In the first female (shown at A, in fig. 8) four nipples are present 

 in a crescentic line upon the right side of the marsupium area, whilst on the 

 left side twin nipples represent the most cephalic member of the series, 

 and a single nipple corresponds to the third member on the right side. 



Fig. 7. 

 Dasycercus cristicauda. 

 Female at the 25 mm. stage to show the 

 marsupium-area and mammary primordia. 















1' 

 11 



o 



o 



o 



ll 













< 



D 



Dasycercus cristicauda. 



Diagram to show the arrangement of the 



nipples in two nursing female specimens 



of Dasycercus cristicauda. 



In the other female (B, in fig. 8) three nipples are on the right, and on the 

 left twin nipples correspond to the first, and single nipples to the other two 

 members of the right-sided series. It is hoped that during the coming season 

 more material of this primitive and interesting didelphian may be obtained, and 

 that further stages of mammary development may be studied. 



