PLATE XV. 



Figs. 1, 1 a. Mertensides diatom, spec. nov. Pages 39 to 40. 



Fig. 1. Portion of a compound pinna of the normal kind. 



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

 Figs. 2-5. Mertensides bullatus (Bunb. species). Pages 35 to 39. 



Fig. 2. Portion of a compound fertile pinna of the most common kind, taken from the lower part 

 of the pinna. 



Fig. 3. Portion of an ultimate sterile pinna, taken from the lower part of the compound pinna. 



Fig. 3 a. Pinnule of Fig. 3 magnified to show nervation. 



Fig. 4. Portion of a compound sterile pinna, showing large heteromorphous pinnules. 



Fig. 5. Portion of a heteromorphous pinnule of the largest size. 



