On the Process of Gastrulation 

 in Chelonia. 



(Contributions to the Embryology of Reptilia, IV.) 



By 



K. IVIilSukuri, Ph. D., Rigakuhakushi, 

 Professor of Zoology, College of Science, Imperial University, 

 Tokyo, Japan. 



With Plates Vr.—VHf. 



The sea-turtle, Clielonia caouana, UVu//. deposits its eg^s 

 on almost every suitable stretch of sandy beacli in the southern lialf 

 of Japan during tlie summer months of the year. During tlie breed- 

 inof season of this animal in 181*1, I Avas enabled, bv the liberaHtv of 

 the University authorities, to visit Sagara in the province of Tötömi. 

 with my assistant, Mr. T. Tsuchida, for tlie pur])ose of collecting 

 materials for the study of its develoj^ment. With the assistance of 

 several kind friends, we made arrangements to luive reported to us 

 every deposit of eggs that might he made along about fifteen miles of 

 sandy beach in that region, and we thus succeeded in getting hold of 

 several good deposits. As encli of tliese contained over one hundred 

 Ggg^ — 1-1 i"^ the least, and 145, the largest number in one deposit in 

 my exjierience, but 16!) has been i-ej^orted in one case— we had command 

 of over one thousand eggs in all, and as we opened eggs from each 

 deposit at certain intervals of time, we were able to secure unusually fine 

 series of embryos, gaps in one series ])eing often filled up by members 



