ii Plate hi. 



Fig. 22. — Dorsal view of the posterior half of an embryo of Trinnyx japonicus with 

 about 10 mesoblastic somites, taken ont S\ days after its deposition. 

 Similar to Cnntrib. H, PI. Ill, Figs. 19 and 19«. The amnion leaves 

 only a small posterior portion exposed. The white lines which mark the 

 internal limits of the extra-embryonic cœlomic cavities are still wide apart 

 even in the mid-dorsal region. They diverge posteriorly. See p. 29. 

 Sections Series VI (PI. V). JA x 2. (143 ffl) 



Fig. 23 — Dorsal view of the posterior half of an embryo of Trioin/.v japonicus taken 

 ont 8è days after its deposition. See p. 29. A A x 2. (142 Û) 



Fig. 25 — Dorsal view of the posterior portion of an embryo of Trioui/.r Japonicus with 

 about 13 mesoblastic somites, taken out 9^ days after its deposition. The 

 white lines making the internal limits of the extra-embryonic cœlomic 

 cavities diverge over the posterior portion cff the embryo, but the cavities 

 have now gone around the posterior outline of the embryonic region and 

 fused into one behind the embryo. See p. 80. Sections Series VIII. 

 (PI. VI). AAx2. (151 ffl) 



EiG. 26. — Dorsal view of the posterior portion of an embryo of Trionyx Jaj>oiiiciis 

 with about 15 mesoblastic somites, taken out 10^ days after its 

 deposition. The amnion has covered the entire embryo-body and ex- 

 tended just one step farther posteriorly. The extra-embryonic cœlomic 

 cavities have not yet extended into the posterior part of the amnion, but 

 diverge at that point. They go clear around, and unite behind, the 

 embryonic region. See p. 30. Sections Series XII. (PI. VIII). AAx2. 



(157 m) 



