78 



K. MITSUKURI; 



In the three species studied the hlastoporic passage once formed 

 is not closed and opened again, as affirmed by Mehxert ('91) and 

 Will ('92 &'93) for Emi/s, Platjidachjilus, and Cistiulo. It becomes 

 directly transformed into the nearenteric canal. 



Of" the surface views given, Figs. l-S belong to Chelonia caouana. 

 Figs. 9-15 to Clemiuiis japonica and Figs. 16-26 to Trioniix japonicus. 

 The following table shows to which species different series of sections 

 belonçr : — 



If the reader will take the trouble to glance over these figures and 

 series, he will, I think, justify the conchision that the course of changes 

 as depicted in the preceding pages has been preserved most plainly in 

 Chelonia caoiiana, somewhat less so in Cleniniijs japonica, and is most 

 abbreviated in Triotujx japonicm. 



As to what hght, if any, the developmental changes here brought 

 out throw on the question of the growth in length of the em- 

 bryo, I may say that so far as the examination of normal embryos 

 shows, there is nothing to indicate that the anterior part of the embryo 

 is formed by concrescence and not by intussusception. In the pos- 

 terior part i.e., in the part formed from the " Endwulst," the story is, 

 however, plain, the formation of that part of the embryo by the 

 coalescence of the blastopore lips being clearly pointed out. I shall 



