3^! K. MITSUKURI. 



General Considerations. 



The notewi^rthy features in the history of the foetal meniliranes 

 of Chelonia as given above are : — 



1. The presence of the Proamnion and the manner 

 in whicli it is replaced by the jiermanent Amnion. 



2. The presence of a pecnliar tube stretchinis- 

 posteriorly from the posterior end of the Amnion 

 e o n n e c t i n g the c n v i t y of the latter with the ex- 

 terior — the Posterior Tube of the Amnion. 



3. The permanence of the Sero- Amniotic Con nee - 



t i O 71 . 



4 . T h e d i tf e r e n c e s in the fa te of t h e S e r o - A m n i o t i c 

 Connection in Tri(^nyx and CI em my s , 



5. The presence (^f the rudimentary "Placentn." 

 Of these, the iirst point has been noticed in nearly all tlie 



amniotn wliose development has lieen carefully studied within reeent 

 years. The only new feature is the fact thnt the dorsal part of the 

 proaniîuon consists at tirst solely of a solid sheet of epibhist 

 cells. The second, thii'd, and foiu-th points are. so far as 

 I am aware, broiiuht out for the first time in the coiu'se of the 

 present investigatioji. They certainly are vovy I'emarkable features, 

 and, so fai" as (»ur present knowledge goes, might be looked on as 

 distinctive of tlie ("heloniati fietal ]n«'inbi'anes. 1 think it, however, 

 highlv |)rol)aMe that if other gi-oiips of |{e|»riHa aii<l lîirds are 

 careful] V gone o\('i' again, maiiv struct ures wliicli are liighh sio-ui- 

 ficant in the light of the facts now <)btaine(l will lie found to have hitherto 

 escajied notice oi- been laid aside ;is iniim|>ortaiii . l^'or instance, in 

 the sections of Lacei'ta gi\(Mi bv se\(M"al antliors. the sero-aiiiniotic 

 connection is (listinetively lii^iu'ed v.xrw up to comparatively late 



