PLATE XXIV. 



PAGK. 



Fig. 1. SyRINGOSTROMA COLUMNARIS 253 



1. Fragment. Natural size. 



la. Vertical section of a fragment. Greatly enlarged. 



Fig. 2. Syringostroma densa 251 



2. Portion of the surface of a fragment. ISTatural size. 

 '■2a. Small portion of the surface. Enlai'ged. 



26. Vertical section of a fragment. Enlarged. 



Fig. o. Strojiatopora nodulata 249 



3. Fragment of a mass. Natural size. 



3rt. Surface of one of the layers. Enlarged. 

 3i). Vertical section of a fragment. Enlarged. 



Fig 4. Strojiatopora ponderosa 246 



4. Portion of the surface of a large mass, showing oscula. Natural size. For the sake of 



simplicity, it has not been attempted to represent on this scale the tubercles which cover 



the entire surface. 

 4a. Portion of the surface of the same, showing the tubercles with their perforated siimniits. 



Enlarged. 

 46. Vertical section of a fragment. Enlarged. 



Fig. 5. Stromatopora sub-striatella 248 



.5. Portion of the surface, showing oscnia and pores. Enlarged. 



5«. Vertical section of the same. Enlarged. , 



Fig. 6. Dicty'ostroma undulata 254 



6. Vertical section of a fragment. Natural size. 

 6a. Upper surface of a fragment, showing the oscula. Natural size. 

 66. Upper surface of one of the internal layers of the mass. Enlarged. 



6c. Vertical section of three layers, showing the perpendicular processes and the ends of the 

 horizontal canals which perforate the layers. Enlarged. 



