PLATE 2 



EXPLANATION OF FIGURES 



11a Transverse section of the right pronephros of Bdellostoma no. 10, illus- 

 trating the three-sided shape. 



12 Millimeter paper reconstruction of the right pronephros of Bdellostoma 

 no. 15. X 25. 



13 Pronephric tubule with funnel-shaped mouth. 



14 Pronephric tubules in longitudinal and transverse section. Bdellostoma 

 no. 15. 



15 Transverse section through two pronephric tubules showing relation of 

 the vascular endothelium to the tubules when a blood sinus occupies the space 

 between the tubules. Bdellostoma no. 15. 



142 



