PLATE I. 



Spirastrella purpurea (Lmk.) Rdl. 

 (Photo's after the original specimens). 



Fig. i. S. E. 300. Cake- or cushion-shaped specimen seen from above. Natural size. 



Fig. 2. S. E. 944 a. Side view. At a one of the tubes, longitudinally cut ; at the bottom an ophiurid (è). 



Natural size. 

 Fig. 3. S. E. 612 d. Side view; the basis almost entirely covered with fragments of shells and other 



calcareous matter, a Holes of barnacles. Natural size. 

 Fig. 4. S. E. 98. Specimen seen from the top. Natural size. 



Fig. 5. S. E. 1403. Coralline alga partly covered with Spirastrella; a young processes. Natural size. 

 Fig. 6. S. E. 948 d. Side view of a process, probably torn off from a large specimen. Natural size. 

 Fig. 7. S. E. 948 c. Fragment with three processes. Natural size. 

 Fig. 8. S. E. 1075. Coralline alga partly covered with Spirastrella, somewhat older than S. E. 1403 (Fig. 5), 



possessing large processes. One of these is torn of at a (compare next figure). 



Natural size. 

 Fig. 9. id. Side view of the process belonging to specimen 1075. Natural size. 



