Fig. 22 Cross section through the anterior i)art of the orbito-tenii)()ral region 

 of an embryo having a carapace 7 mm. long, showing the sei^tum infeiorhil ale 

 much thicker from side to side than in an older embryo. X 15. 



Fig. 2;i Cross section through the same embryo as the ])receding, somewhat 

 further anterior than the previous figure, showing the septum interorbitale (.s./.) 

 made u]) of two parallel plates which later become pressed togetlier on the middle 

 line. X 15. 



774 



