54 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



EXPLANATION OF PLATE V. 



NitophylluiH ander sonianuni . 



Fig. 18. Robust form, sterile, showing usual character of branching, with 



branches flabellately expanded at apices. One-third natural size. 

 Fig. 19. Broad membranous form of quiet waters, sterile. One-third natural 



size. 

 Fig. 20. Slender form, sterile, showing fine dissection of frond. One-third 



natural size. 

 Fig. 21. Transition form, tetrasporic, much branched, showing tendency to 



become membranous. One-third natural size. 



