Dorsal view and median reconstruction of No. 7801 stage 6, in alignment. The dorsal view, which is based on a graphic reconstruction by the present writers, shows the location of the primitive streak and primitive groove. The median reconstruction is based on a drawing by James F. Didusch (Heuser, Rock, and Hertig, 1945, Plate 3). The primitive streak is indicated by vertical lines, and the cross-hatched area (containing a question mark) suggests the site of the future cloacal membrane. The connecting stalk comprises amnio-embryonic and umbilical stalks. The figure references are to the sections reproduced by Heuser, Rock, and Hertig (1945, Plates 1 and 2).