PLATE XVI. 



Figs. 1-3. Mertensidcs bullatus (Bunb. species). Pages 35 to 39. 



Fig. 1. Portion of a compound fertile pinna, showing the diminution in number of the sori towards 

 the summit of the pinna. 



Fig. 1 a. Pinnules of Fig. 1 magnified to show the fructification and nervation. 



Fig. 2. Portion of the upper part of a compound sterile pinna showing uncommon form of the pin- 

 nules. 



Fig. 2 a. Pinnules of Fig. 2 magnified to show nervation. 



Fig. 3. Portion of a compound sterile pinna showing an unusual form for the pinnules. 



