EMBRYOLOGY OF THE LOWER VERTEBRATES CH. 



shaped Lfastrular lip corresponds to the yolk -plug of 



A 



* *'' "''''- "" 



B 



end' 

 ent 



y? 



31. Sagittal .sections tlnougli early st;i-v> o!' /'/,// i// ,/,,,-//////.s-. (Altrr Will, 1892.) 



A is of the Kta-i* shown in Kin. -"'- A ; E is of (),. sta.^-- of Fig. l _'9, B; B, C, ami Dan- <it iiitrnii.-iliatf 

 stages. e., embryonic Hhi<'M ; c t /, i-ct. nil-mi : Muf, sn ..... d.-nx rn.lodi-i in ; nU, an-limtn ic <-avitv : 

 .'/./, nati i! lai lij>; ///./<, t hickiMUM] ctodiTin wliicli will ;ji\c i :.-. lali-r i<> tin- mitral m-rvons sxstt'iii 

 Oii-ilnllaiy plat*-); p.p, \>i iinit ivc |>lai- : //.//. \-olk-jilnn. 



ani])liili;ins ami in sun- cases ton ( l.,i,- t rh( Will) it become- 



<-nclosed, the tips of the, horsr-shoe c-urvin-j- inwards and 



