PLATE XXV. 



I'Ac;e. 



l^g. 1. HlPPOTHOA INFLATA 268 



1. A small fragment. Natural size. 



la. The same. Enlarged 



\h. Two of the cells of the same, enlarged still finllu-i'. 



Fig. 2. Alecto auloi'oroides 267 



• 2. A pnrtiou of the polyzoary "Towiiig upon Strophomena alternata. Greatly enlarged. 



2«. Portion of the same, showing biserial cells. Gi-eatly enlaigt'd. 



'2b. Another branch of the same, showing more or less completely nniserial cells. Greatly 

 enlarged. 



Fig. o. Alecto erondosa 266 



:'.. Portion of the polyzoary growing upon Strophomena alternata. Natural size. 



"ia. Portion of the same. Enlarged 



:V). Fragment of the .same. Greatly enlarged. 



Fig. 4. ■ Ptilodictya flagelia'm 262 



4. Frond, broken above. Natural size. 

 Aa. Transverse section. Enlarged. 



iti. I'oition of the frond. Greatly enlarged. 



Fig. 5. Ptilodictya e.macerata 261 



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

 5a. Transverse section of the same. Enlarged. 

 fih. Poi'tion of the sanse. Greatly enlarged. 



Fig. 6. Alecto confusa 267 



fi. Polyzoary formiog a c rusji on a erinoidal column. Nfitural size and enlarged. 



Fig. 7. Ptilodictya falcifokmls 259 



7. A small example. Natural size. 



7a. Transverse section of the same. Enlarged. 



7ft. Portion of the surface rtf the same. Greatly enlarged. 



Fig. 8, Ptilodictya fenesteli.iformis 263 



.•=L A small fragment. Natural fcize. 



8a. Transverse section of the same. Enlarged. 



.■<^j>. Poi'tion of the aurface of tb« same, showing one of tlu' non-celluliferous areola-. Enlarged. 



Fig. 9. Ptilodictya (?) .\lctipora 202 



9. I*\'agment of a «ylindritv'd fiond. Natural size. 



9a. Portion of the same. Enlarged. 



9/). A few <!eife. Greatly enlarged. 



Fig. 10. Ceramopora Ohioensis " 265 



19. A small portion of the crust. Enlai'ged. 



10a. A fe,w cells of the same. Greatly enlarged. 



lOi. A few ■cells from a worn specimen, (ireatly enlarged. 



I'Oc and lOe?. Portions of the surface of mucli worn specimens of the same \l), sliovvinsi numer- 

 ous interstitial tubuli. (ireatly enlarged. 



lOc, Young colony of the same. Enlarged. 



Fig. 11. Fenestella nervata 264 



IL Praginent of this frond. Natural .size. 



Ma. Portion «f tbe same. Kidarged. 



