PLATE V. 



Archaeolithothamniou erythraeum (Rothpl.) Fosl. f. dura (Heydr.) Fosl. 



Fig] i. A. piece of the type specimen from El Tor (Ex coll. Rothpletz). 



Fig. 2. A piece of an authentic specimen of Sporolithon ptychoides f. dura Heydr. from El Tor. 



Fig. 3 — 4. Fragmentary specimens from Obock in the Gulf of Aden. 



Fig. 5. A specimen surrounding some hard object, forming transition to f. mollis. Stat. 193. 



Fig. 6. A typical specimen. Stat. 193. 



Fig. 7. An older specimen surrounding some hard object, in the part tuining upwards rather worn by 



the action of a strong current. The edges of some of the worn branches are in part covered 



by new formations of tissue issuing from the undamaged parts of the plant. Stat. 193. 

 Fig. 8. A specimen with coarse branches, the thickness of the latter is however, at least in part, owing 



to their covering up extraneous objects, or to new crustlike formations over the primary 



branches. Stat. 99. 

 Fig. 9. A similar specimen seen from the side. Stat. 99. 

 Fig. 10. A specimen with less crowded branches, the thickness of the latter at least in part also owing 



to their covering up extraneous objects. Stat. 234. 

 Fig. 11. A specimen almost covering Goniolithon Reinboldi attached to a coral. Parts of the latter species 



with conceptacles are visible at the top and to the right on the figure. East-Indian Archipelago. 



Stat. unknown. 

 Fig. 12. A specimen attached to a coral, rather hollowed by worms and much burdened with other 



foreign bodies. Stat. 234. 



