8 



( '< .M 1'ARATIVE ANATOMY. 



Fie. 7, A AMI !'.. Di \<;I:AMMATIC TKANSYK I:SK Sn TIMNS THKOfGii A DEVKI.OI-IN<: 



VERTEBUATE EMHKYH. 



D, alimentary cu\\:i\ ; Eiit, hyjinhlast, slm\vin^ in Ki^. A the tliii-kcning \vliirli will 



form til.' liiil.irlmril ; Cll 1 (Fig. H\ tll(! Iiotcirlinvd liuW rolistl -ictc (! nil' IVnlll till' 



liypnlilast ; I'll', mrMiUastir, sninitc ; ft,', niiinaiv urinnry iluct lsci,'i]i-nt:il 

 ilil'-l ) ; A. :mrt:i ; N///', spl.-mrlmir and ,S'i/', sniiiatii 1 nii'snMasI ; ' '</. ( ViV, rn Ininr ; 

 //, remains nf the upper part of tin; en-Ionic in Ilir interior of the mesohlastie 

 somites ; Kkt, ejiihlast ; .!/'</, nicdiillary i-oi'd : in IML,'. A it is shown still con- 

 nected with the epiMa^t, fioiu which it has become constrirtrd oil' in Fi^'. 15. 



A lari;i' <-lftt .Mjipfurin^ in tin- uicsuliL-istic tissue divides it into 

 a parietal layrr Ki^. 7, A and B, X^/' 1 , lying along the inner 



