PLATE XX. 



Fig. 1. Millepora alcicornis Lamarck, natural size. 



Fig. 2. Millepora alcicornis Lamarck, branchlet .seen from above, natural size. 

 Fig. 3. Millepora alcicornis Lamarck, branchlet seen in profile. 



Figs. 4, 5. Millepora alcicornis Lamarck, vertical and horizontal sections of corallum, showing the trans- 

 verse floors (tabulae) of the calicles. 

 Fig. 6. Millepora alcicornis Lamarck, surface magnified, showing the two kinds of calicles. 



