HUBRECHT. Pl. X. 
115 116 
Fig. 115 and 116. Two surface views of early blastodisks of Ornitho- 
rhynchus (after Wilson and Hill, 07). In Fig. 115 the protochordal wedge (pw) 
and the ventral mesoblast 7 are yet wide apart; in Fig. 116 they are fused in 
the median line and proliferation takes place along the whole length of the 
dorsal mouth, sc notochord. — Fig. 117 to 119. Three longitudinal sections 
through consecutive stages of notogenesis of Torpedo (after His, “00). In Fig. 117 
ectoderm /ec) and entoderm /e/) have been separated by delamination and noto- 
genesis has commenced; in Fig. 118 the folding off of the head has proceeded 
further; in Fig. 118 and 119 part of the protochordal plate is being lifted up 
from the yolk. £f protochordal plate, cz notochord. 
