PLATE III. 



Figs. 1-4. — Plumularia abietina. 

 Fig. 1. — Natural size, with young Avicula-like Mollusca attached to the stem and branches. 

 Fig 2. — Portion of hydrocladium magnified ; lateral view. 

 Fig. 3. — Same ; front view. 

 Fig. 4. — Portion of a branch with gonangium. 



