Miastor ? americana Felt 



Young embryo dissected from a large mother larva and showing a darker 

 strip of ectoderm, a lighter mesodermal area and a dark mass of tissue at 

 the anterior extremity toward the left, x lOO 



Young living embryo lying mostly in the ninth segment of a small, yel- 

 lowish mother larva. Note the large polar cells at the lower posterior ex- 

 tremity. X 200 

 The same, more enlarged, x 400 



164 



