The development of the urinogenital organs of the lamprey. 



83 



Description of the Plates. 



Plate 1—7. 



Reference Letters. 



ao aorta 



1)1 blood corpuscles 



C heart 



ca corpus adiposum 



CC central canal 



cd collecting duct 



ch chorda 



ch.s chorda sheath 



coe coelom (myocoele and splanchn- 



ccele) 

 cpl cutis plate 

 cv cardinal vein 

 d pronephric duct 

 ec "Ersatzzelle" 

 ect ectoderm 



end endothelium of bloodvessels 

 ent entoderm 

 ff dorsal fin-fold 

 gla glomerular artery 

 glv glomerular vessel 

 gom reproductive cells 

 int lumen of intestine 

 Im parietal mesoderm 

 m middle plate 

 mc myocomma 

 mes mesonephric tubule 

 mes. h band of peritoneum giving 



rise to mesonephric tubules 



mes.f mesonephric funnel 



mpl muscle plate 



ms mesoblastic somites 



mp myotome 



n neural tube 



p somatic layer of nephrotome 



pg pigment 



pron^, pron^ etc. 1st, 2nd etc. pro- 

 nephric tubules 



pron.f pronephric funnel 



pron.gl glomus (pronephric glome- 

 rulus) 



pt peritoneum 



sch sub-chorda 



scl sclerotome 



ses sub- cardinal blood sinus 



spl splanchnopleure 



som somatopleure 



sp.v spiral valve 



vf ventral fin-fold (?) 



vs venous sinus (enclosing pro- 

 nephric duct) 



X lateral boundary of mesoderm 

 and entoderm 



2/ boundary between segmented and 

 unsegmented mesoderm 



boundary between myotome and 

 nephrotome. 



6* 



