PLATE XXIII. 



rAGB. 

 Fig. 1. AULOPORA AKACHNOIDEA 216 



1. A specimen in which the branching is regular and no close reticulation is formed, growing 



upon the st«m of a ramose Cfuxtetes. Natural size. 

 la. The same. EnlarMd. 

 1&. Portion of a brancn. Enlarged still further. 



Fig. 2. AcERVULARiA Clintonensis 227 



2. A few of the calices of a weathered specimen. Natural size. 

 2a. Transverse section of two corallites. Enlarged. 



Fig. 3. Favosites pleurodictyoides 231 



.3. Under side of a small specimen, in which part of the epitheca is preserved. Natural size. 

 3a. Under side of a decorticated specimen, from which the epitheca nas been removed, show- 

 ing the mural pores on some of the best preserved corallites. Natural size. 

 3&. Portion of the wall of a corallite, ahowing the mural pores. Enlarged. 



Fig. 4. Cystiphyllum Ohioense 234 



4. An adult specimen, viewed in profile. Natural size. 

 4a. CaUco of the same. Natural size. 



Fig. 5. Zaphrentis Wortheni 235 



5. A specimen viewed laterally, so as to show the extreme obliquity of the calico. Natuial 



size. 



5a. The same, viewed from the front. Natural size. 



Fig. 6. Zaphrentis Edwardsi 235 



6. Side view of a specimen. Natural size. 

 6a. Calice of the same. G-reatly unlarjied. 



Fig. 7. Favosites invaginata _. 232 



7. Corallum, of the natural sixe. For the sake of simplicity, the calices which cover the entire 



upper surface are omitted. 

 7a. A few of the calices. Enlarged. 



