The germ ring has now taken an almost equatorial position on the surface of the yolk, i.e., about one-half of the yolk surface is covered by periblastic ectoderm. The embryonic shield is 0.6 mm. long and 0.25 mm. broad at the middle (fig. 2D). The neural keel is formed in the anterior two-thirds of the shield (fig. 2E, F).