PLATE XXIII. 



LICHENALIA. 



(Page 559.) 



Lichen ALIA substellata, Hall. 

 Fig. 1. A frond, natural size. 



Upper Helderberg group. Falls of the Ohio, 



LiCHENALIA OVATA, Hall. 



Fig. 2. A frond, natural size. 



Upper Helderberg group. Falls of the Ohio . 



LiCHENALIA VESICULATA, Hall. 



Fig. 3. A frond incrusting a Cyathophylloid^coral, natural size. 

 Hamilton group. Western New York, 



LlCHENALIA SUBTKIGONA, Hall. . 



Fig. 4. An enlargement of a vertical section, showing the internal 

 structure of the family Fistuliporid^. x6. 

 Hamilton group. West Williams y Ontario. 



LlCHENALIA LUNATA, Hall. 



Fig. 6. An enlargement of the surface, showing the form and 

 arrangement of the denticulated cell apertures and monti- 

 cules. x6. » 



Fig. 6. A specimen fractured so as to show the internal structure. 

 The pseudo-septa and tabulae of the cell tubes showing very 

 plainly. x6. 

 Upper Helderberg group. Falls of the Ohio. 



LICHENOTRYPA. 



(Page 556.) 



LiCHENOTRYPA LONGISPINA, Hall. 



Fig. 1. An enlargement, showing the form and arrangement of the 

 cell apertures, the interapertural elevations^ and the spines 

 at the angles. x6. 

 Upper Helderberg group. Falls of the Ohio. 



