34 K. MITSUKUitl. 



the latter with the .sero-anmiotic coiiiiectioii is now ,so dispropor- 

 tiunatelv small (-(Jtupared with the aiiiiiiou itself that it appears as a 

 small irivi;-iilai'ly triaiiuuhir white pateh (l"'i,u". 8L(f, Aiit. Proloiiii'. 

 Amii., and 1' i;L:. <Sl). Its oaA itv. n(3w ahiKJst ohliterated t)\' the aj)pres- 

 sion of its two walls, js still ('ontiniKjiis with the amniotie cavity 

 throiiiih n narrow slit (see Via;, (ila and Diaii'. A'll). It leads to the 

 sero-anmiotic connection. I'ig«. 82-85 (PI. IX.) are a series of sec- 

 tions of this region, the plane of sections being in the antero-posterior 

 direction. Fig. 82 is from the left side of the triangular unc(jvered 

 area, in Fig. 81« (or from tlie right side in Fig. 81). The two 

 allantoic lobes, the anterior and posterior, are only slightly apart from 

 each other. Attention is called specially to the section of a part of the 

 anterior prolongati(jn. Figs. 83 and 84 are from the triangular area 

 itself. Here the two allantoic lobes are wide a})art. The interspace 

 is tilled up mostly by the growth of the somatic mesoblast of the 

 serous envelope. The sero-anmiotic connection in Fig. 83 is of a 

 very complicated figure. This arises from two reasons. Jn the 

 first place, the section being taken in the antero-posterior direction, 

 it cuts ()ne lindj of the horse shoe shaped sero-amniotic (.-onnectioji 

 more or less longitudinally. In the sectjnd place, the sero-amniotic 

 connection is not in a simple straight line as in (Jlemmys, but 

 being compressed and rultled. ap])ears as of an irregular ])attern 

 in a section. In Fig. <S4, the sero-amniotic (•onnection is cut nnjre 

 directly across. To give an idea of the structiu'e of this region. I 

 have gi^ en a. part of Fig. 84 on a more enlarged scale in 1 ig. 84(/. 

 In Fig. So. wlii<-li was hi-oken by accident, the two allantoic lobes 

 have again a])j)roached eiicli other, the section being out of the 

 triangular area. The\" are, however, distinct and continue distinct 

 until the sections reach the allantoic vessels. 



In Tri onyx, the renuiant of the posterior tube of the allantois 



