134 J. p. HILL. 



The sliell-niembnme varies in thickness in the sections from 005 mm. 

 over the former region to VO'S mm. over the latter. 



Figs. 83, 84, 85. — Drawings ( x 630) of small portions of the formative 

 (and in fig. 83 of the adjoining portion of the non-formative) region of 

 the above blastocyst of M. rnficollis more highly magnified, ent. 

 Primitive entodermal cells. Note in fig. 83 a cell of the wall in division, 

 the axis of the spindle being obliqne to the surface. 



