T. H. BURLEND, 



Thus at the period when only five or six protovertebrae are 

 present the kidney is in its initial stage of development and presents 

 most primitive characters. It appears as a groove in the somato- 

 pleure, traces of it being visible in segments II, III and IV and 

 more obvious rudiments in segments V and YI. 



There is no trace of the kidney behind segment VII. 



Left side 



Embryo A. 

 1,1 (Body begins) 



Right side 



1,16 



"{ 



III 



IV 



VI 



1,31 



2,8 



2,23 



2,38 



3,14 



3,29 



4,4 



4,19 



ear 



I 



II 



III 



IV 



V 



YI 



iScale = 3 sections 

 to a division) 



4,34 



5.11 



neurenteric 

 canal 



