C. Older blastoderm with embryo in which neural canal has become formed, and is continuous posteriorly with alimentary canal. The notochord, though shaded like mesoblast, belongs properly to the hypoblast.
Fig. 2.
Diagrammatic longitudinal sections of embryo, which develops in the same manner as the Elasmobranch embryo, but in which the ovum contains far less food-yolk than is the case with the Elasmobranch ovum.
Epiblast without shading. Mesoblast black with clear outlines to the cells. Lower layer cells and hypoblast with simple shading.
ep. epiblast. m. mesoblast. hy. hypoblast. sg. segmentation cavity. al. alimentary cavity. nc. neural canal. hf. head fold. n. nuclei of the yolk.
The stages A, B and C are the same as in figure .[TN9]
Fig. 3.