Plate XI. 



Arabic numerals placed between every two sections indicate the number 



of sections that intervene between those two (exclusive). 



Certain ujarks on the left of each section are for the identification of the 



sections and do not concern the reader. 



Series XVI. a-Z. — Sections through an advanced embryo of Chelonia caouana taken 

 out 16 days after deposition, with five gill slits all formed, the cranial 

 flexure well marked, and the appendages knob-like. About the stage of 

 Contrih II, Fig. 11 and 11a. For detailed description see. p. G8. a-j) 

 a«x2; q-zAAx2. (^7^^) 



Sero-Amn. Conn ^= Sero-amniotic connection. 



Coel.^ = Extra-embryonic body-cavity. 

 (The numeral between j and k should read instead of 6.) 

 Series XIV. k' — The ventral median part of tlie tail in Section /.■ in the above series 



more highly magnified. DDx 4. 

 Series XIV. /' — The ventral median part of the tail in Section / in the above series 

 more highly magnified. DD x 4. 



Hi//>. = Hypoblast. 



Mes. = Mesoblast. 



Ejii. = Epiblast. 



