PLATE XIX. 
Figs. 1-3—Azygoplon rostratum. 
1.—Natural size. 
2.—Portion of a hydrocladium, magnified ; lateral view. 
3.—Portion of stem with hydrocladia and gonangia ; front view. 
Figs. 4-6.—Lytocarpus longicornis. 
4.—Natural size. 
5.—Portion of hydrocladium ; magnified. 
6.—Portion of a primary pinna, with origins of hydrocladia. 
Figs. 7-9.—Aglaophenia courctata. 
7.—Natural size. 
8.—Portion of hydrocladium ; magnified. 
9.—Portion of a branch with origins of hydrocladia, showing wedge-shaped inter- 
nodes. 
