PLATE XXIII. 



TkEMATOPORA (OllTHOrORA) REGULARIS. 



Page 16. 



See Plates 11 and 13. 



Fig. 1. An enlargement of a portion of a specimen showing the cell apertures obscured by the prominent, 



nodose longitudinal ridges. (X 18.) 



Lower Heldei-berg group. Clarksville, N. Y. 



Tkematopoka (Outhopoka) qranilinea, u. sp. 



Fig. 2. An enlargement of a jjortion of a spei^imen, showing the form and an-angement of the cell 

 apertures, the nodes and granulose striationa of the sui-face. (X 18.) 

 Lower Heldorlierg gi-ouji. ClarksviUe, N. Y. 



Caixopora (Callotrypa) heteropora. 



Page 25 

 See Plates 11 and 13. 



Fig. 3. An enlargement of a portion of a specimen, showing the form and arrangement of the cell 

 ajiertui-es and mesopores. (X 18.) 



Lower Helderberg group. Clarksville, N. Y. 



FlSlXLlPORA, sp. ? 

 See Plate 14. 

 Rg. 4. An enlargement of a portion of the surface, showing the form and arrangement of the cell aper- 

 tui-es and mesoporea. (X 18.) 



Trematopora (Okthopoba) ovatipora. 



Page 17. 

 See Plate 11. 

 Fig. 5. An enlargement of a specimen, showing the form and an-angement of the cell apertui-es, their 

 grannloae margins, the node at the base of each aperture and the nodose longitudinal ridges 

 separating the ranges of apertures. (X 18.) 



Lower Helderberg gi-oup. New Salem, Albany Co., N. T. 



Callopora (Callotrypa) occulifera. 



Page 27. 

 See Plate 13. 

 Fig. 6. An enlargement showing the foi-m and arrangement of the cell apertures and mesopores. (X 18.) 

 Lower Helderberg group. Clarksville, N. Y. 



Trematopora (Orthopora) parallela. 



Page 19. 

 See Plate II. 



Fig. 7. An enlargement showing the peristomes in contact and a pominent node at each angle. (X 18.) 



Lower Helderberg group. Clarksville, N. Y. 

 Fig. 8. An enlargement showing the longitudinal ranges of apertures separated by nodose ridges. ( X 18. ) 



Lower Helderberg group. ClarksviUe, N. Y. 



Trematopora (Orthopora) canaliculata. 



Page 17. 

 See Plate 11. 

 Fig. 9. An enlargement showing the foi-m and arrangement of the cell apertures. (X 18.) 

 Lower Helderburg group. New Salevi, AUxv^y Co., N. Y. 



I 



