PLATE XXV, 



PAGE. 

 Fig. 1. HiPPOTHOA INFLATA 268 



1. A small fragment. Natural size, 

 la. Tho same. Enlarffort 



1&. Two of the cells of the same, enlarged still further. 



Fig. 2. Alecto auloporoides 267 



2. A portion of the polyzoary growing upon Strophomena altemata. Greatly enlarged. 

 2a. Portion of the same, showing biaenal cells. G-reatly enlarged. 



2&. Another branch of the same, showing more or less completely tiniserial cells. Greatly 

 enlarged. 



Fig. 3. Alecto frondosa 266 



3. Portion of the polyzoary gi'owing upon Strophomena altemata. Natural size. 

 3a. Portion of the saine. Enlarged 



3ft. Fragment of the same. Greatly enlarged. 



Fig. 4r. Ptilodictya flagellum 262 



4. Frond, broken above. Natural size. 

 4rt. Transverse section. Enlarged. 



4&. Portion of the frond. Greatly enlarged. 



Fig. 0. Ptilodictya emacerata 261 



5. A fragment, of the natural size and enlarged. 

 5a. Transverse section of the same. Enlarged. 

 5&. Portion of the same. Greatly enlarged. 



Fig. 6. Alecto confusa 267 



6. Polyzoary forming a crust on a crinoidal column. Natural stee and enlarged. 



Fig. 7. Ptilodictya falciformis 259 



7. A small example. Natural pize. 



7a. Transverse section of the same. Enlarged. 



V). Portion of the surface of the same. Greatly enlarged. 



Fig. 8. Ptilodictya fenestelliformis 263 



8. A small fragment. Natural size. 



8a. Transverse section of the aam(\ Enlarged. 



H&. Portion of tJie surface of the same, showing one of the non-celluliferons .iretolai. Enlarged. 



Fig. 9. Ptilodictya (?) arctipora 262 



9. Fragment of a cylindrical frond. Natural size. 

 9a. Portion of the same. Enlai'ged. 



Uh. A few cells. Greatly enlarged. 



Fig. 10. Ceramopora Ohioensis 265 



10. A small poi-tion of the crust. Enlarged. 



10a. A f^w cells of the same. Greatly enlarged. 



106. A few cells from a worn specimen. Greatly enlarged. 



lOc aiid iOd. Portions of the surface of much worn specimens of the same (?), showing numer- 

 ous interstitial tubuli. Greatly enlarged. 



lOi?. Young colony of the same. Enlarged. 



Fig. 11. Fenestella nervata 264 



n. Fra^ent of this frond. Natural size. 



11a. Portion of the same. Enlarged. 



