Plate 15. 



Plumularia helleri, page 18. 



Fig. 1. A colony, natural size. 



Fig. 2. Part of a colony, x 75. 



Fig. 3. The basal portion of a stem, x 60. 



Fig. 4. Part of the main stem of a second colony, x 50. 



Fig. 5. A pinna from figure 4. x 50. 



Fig. G. An internode enlarged, x 125. 



