Plate IX. 

 Fig. 27. Stage VII. Showing the union of the cerebral and optic ganglia 

 to form tlie pro-cephalic lobes, the deepening of the anterior and lateral 

 optic invaginations to form vesicles, the optic thickening which forms the 

 rudiment of the lateral eyes, /. e., the increased growth of the optic fold, 

 the shifting of the rostrum posteriorly until it completely covers the 

 stomodieum which is flanked on either side by the neuromeres of the chel- 

 iceral segment, also the ectodermal pit, e. p. 



Fig. 28. Stage VIII. Showing the narrowing of the anterior portion of 

 the head region, the increased grow^th of the optic fold, and the general con- 

 crescence of the optic and cerebral ganglia. 



