EXPLANATION OF PLATE IV. 



Fi<;. 7 Photomicrograph of section of cephalic extremity of embrvo kitten 

 about seventeen millimeters in length. Another section from same 

 series as Figures 5 and 6. 

 P. I. Processus infundibuli. 

 H. C. Hypophysis cerebri. 

 A. C. V. Anterior cerebral vesicle. 

 M. C. V. Middle cerebral vesicle. 

 P. C. V. Posterior cerebral vesicle. 

 Phar. Pharynx. 

 Fiy. 8. Photomicrograph of the region under consideration, from the same 

 sectiOii, enlarged. 

 P. I. Procsssus infundibuli. 

 H. C. Hypophysis cerebri. 



