PLATE XXIV. 

 ODONTOTRYPA. 



(Page 561.) 



Odontotrypa alveata, Hall. 



Fig. 1. A frond, natural size, incrusting a Fbnestella. 



Fig. 2. An enlirgement of a portion of the surface, showing the 



form aud arrangement of the cell apertures and one of the 



maculae. x6. 

 Fig. 3. A still further enlargement. xl8. 



Upper Helderberg group. Falls of the Ohio. 



SELENOPORA. 



(Page 557.) 



Selenopoba cikcincta. Hall. 



Fig. 4. A frond incrusting a Fenestella, natural size. 



Fig. 5. An enlargement of the surface, showing the form and 

 arrangement of the cell apertures and one of the maculae. 

 x6. 



Fig. 6. A still further enlargement, showing more distinctly the 

 denticulated cell apertures and the interapertural eleva- 

 tions. xl8. 

 Upper Helderberg group. Falls of the Ohio, 



Sblenopora complexata, Hall. 



Fig. 7. An enlargement of the surface. 



Upper Helderberg group.- Falls of the Ohio. 



GLOSSOTRYPA. 



(Page 563.) 



Glossotrtpa palifoemis. Hall. 



Fig. 8. Fragment, natural size. 

 Fig. 9. The same. x6. 



. Fig. 10. Section showing cell tubes and thickness of zoarium. x6. 

 Upper Helderberg group. Falls of the Ohio. 



