232 EMBRYOLOGY OF THE LOWER VERTEBRATES CH. 



it is only when nephrocoeles begin to appear (in the regions of the 

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.MJ. nit-lit ol' tin- |iroiu-i>lii-,.> in btgridosiren as -lm\\n in transverse si'rlit.n>. 



A, it I -'-''X 1 ' '21 : ( ', HtaKe '.'44-. "..'/, an-liiin'idiric >hid ; /(/, .ntltnli-nii ; - nt, i-iit.Ti.- 



cavity ; yl, ^lonn-riilus ;/.//-, lat' : iii\ntiiii' : A, nutui'l I; m: iirphnii -.x-lf : /<// 



|.i'u-jilirii' tulMil.-; .>, hj<inal coid ; >.-/, Mi-lerotome. 



lift}) ;uid sixlli 



thai. I In- -;_ incnl.Ml nature of t lit- nulniii'iil 



