FORMATION OP GERMINAL LAYERS IN CHELONIA. 17 



On the Formation of the Germinal Layers in 

 Chelonia. 



By 



K. Hitsukuri, Pli.D., 



Professor of Zoology, 



and 



C Isbikawa, 



Assistant in Zoology, University of Tokyo, Japan. 



With Plates II, III, IV, and V. 



In the spring of 1884 we made the acquaintance of Mr. 

 Hattorij the proprietor of a large fish-hatching establishment in 

 Honjo, a suburb of Tokyo. His father before him, and he, had 

 succeeded in making the snapping turtle — Trionyx Japo- 

 nic us, Schlegel — breed freely and naturally in captivity, and 

 thus in furnishing the market with a constant and large supply 

 of its delicate flesh. In his farm hundreds of these turtles are 

 annually hatched, and if the eggs are marked as they are laid 

 the exact age of any given deposit can be determined with 

 great precision, even to minutes in many cases. Such an 

 opportunity for the investigation of Reptilian development 

 seenaed to us too good to be thrown away, especially as nobody 

 had, so far as we were aware at the time, worked on the em- 

 bryology of Chelonia since the days of Agassiz and Clark, and 

 therefore with modern methods of investigation. Mr, Hattori 

 kindly consenting, we went to his farm daily during the 

 breeding season of 1884 and of 1885, and succeeded in collect- 

 ing a fairly complete series of the Tryonix embryos, beginning 



VOL. XXVII, PART 1. NEW SER. B 



