PLATE XLVIII. 

 Fenestella latijunotuiu. 



I'aife lis. 

 Fig. 1. An enlargement of a jwrtioii of the nou-celluliferous face of a fi-oiid, showing very irregular 

 branches, with frequent elevations ai-ound the lower portion of the fcnestrulea and numeroufl 

 8tn)ng nodes. (X 6.) 

 2. A iMirtion of the non-cellulifei-ous face of a frond. The branches present a very irregular 

 appearance, and many of the .strong nodes are pi-olonged into spines. (X 6.) 

 (lortiou of the celluliferous face of a frond with the carinse removed, showing the foi-m and 

 arrangement of the cell apertures. The bi-anches are remarkably i-egular as compared with 

 the opposite face. The lithogi-aphic figure fails to I'epresent the oi-iginal drawing. (X 6.) 

 lateral view of a branch, showing a transvei-se section of the dissepiments, the cell apertures 

 oi)ening directly outwai-d, and the strongly elevated carina, with its lateral denticulations. 

 transverse section of the branches and carinse. 



Upper Helderberg group. I^alls of the Ohio river. 



Fenestella bi-imbricata. 



Page 121. 

 Fig. 6. An enlargement of the non-celluliferous face of a fi^ond, presenting a very iri-egular appearance, 



making it difficult to distinguish the branches and dissepiments. The surface of the frond 



also has been somewhat affected by macei-ation. (X 6.) 

 Fig. 7. A portion of the non-cellulifei-ous face of a frond, in which the branches and dissepiments cannot 



be distinguished from each other, the face of the frond jiresenting very much the appearance 



of some encrusting zoarium. (X 6.) 

 Fig. 8. An enlargement of a portion of the non-cellulifei-ous face of a frond, showing the branches and 



dissepiments so thickened and involved as to have lost their distinctive character. (X 6.) 

 Fig. 9. An enlargement from the celluliferous face of a frond. The branch at the left of the figure sliows 



the expanded summit of the carina. The two adjacent branches show the interior ; the next 



branch shows the surface neai-ly worn through, and the two branches at the right preserve 



their normal condition. (X 6.) 

 Fig. 10. An enlargement of the summits of the carinte on the celluliferous face. (X 6.) 

 Fig. 11. A transverse section of the branches and carina;. (X 6.) 



Upper Helderberg group. Falls of the Ohio river. 



Fenestella interrupta. 



Page 123. 



Fig. 12. An enlargement of a portion of the non-celluliferous face of a frond which has been woni and 

 ma<;erated. (X 6.) 



Fig. 13. A transverae section of the branches and carina\ (X ti.) 



Fig. 14. An enlargement of a portion of the non-celluliferous face of a frend, somewhat macerated. The 

 branches and dissepiments are essentially undistinguishable fi'om each other and are frequently 

 disposed in a stellate manner. (X 6.) 



Fig. 15. An enlargement from the non-celluliferous face of a fi'ond, showing angidar and cannated 

 branches and dissepiments of nearly equal width, which are so irregularly disposed that they 

 cannot i-eadily be distinguished from each other. (X C.) 



Fig. 16. A portion of the non-celluliferous face of a frond, showing the branches and dissepiments of 

 nearly etjual width, but so irregularly disposed as not to be readily distinguished from each 

 other. (X 6.) 



Fig. 17. An enlargement of a portion of the cellulifei-ous face of a frond of this species. On the left of 

 the figure the carina; are broken away, showing the foiin and arrangement of the cell aper- 

 tures. On the right of the figure the sunnnits of the caiina* are shown. (X C.) (The litho- 

 graphic figure has failed to give the pi-oper effect.) 



Ujiper Helderberg gro' p. l'\dls of the Ohio river. 



