162 Gastrulation and Embryo Formation in Amia Calva 
Fic. 51. Obliquely transverse section of same embryo taken a few sections 
behind that shown in Fig. 50, showing same structures as above. 
Fic. 52. Transverse section of embryo in same stage showing the extension 
of the cavity of the auditory vesicles also the gut and coelomic cavities. 
Fic. 53. Horizontal section through the head region of embryo in same 
stage showing various structures. 
