No. 6.] 



THE HYPOPHYSIS IX CHELO.X1A. 



279 



PLATE III. 



FIG. 4 (PL III), Stage C. Median sagittal section of A. spinifer. 

 Lg. = 5.7 mm. Mesoblastic somites =21. < 50. 



PM. 



FIG. 5 (PI. Ill), Stage D. Median sagittal section of A. spinifer. 

 Lg. 6.0 mm. x 50. 



