PLATS XXVI-CouUnueU. 

 CaLLOPORA (C(EL0CAUL18) ACULKOLATA. 

 Page 76. 

 Fiff. 16. A specimen, natural size, somewhat cruaheil. 



Kg'. 17. An enlargement of tig'. 16, sliowiiifr the form ami arrangement of the cell apertures, the minute 

 spines on the elevated peristomes ami the intermediate pits. (X 6.) 

 Upper Helderberg group. New York. 



./ IIC'III. CaLLOPORA MULTiaEKlATA. 

 Page 75. 

 -- 'See Plate 25. 

 Fig. 18. A specimen, natural size, showing the manner of growth. 



Fig. 19. An enlargement of fig. 18; showing the form and ari-anneineut of the cell apertures and the 

 intermediate pits, so ari'ange<l an to give a sti-iated appearance to the surface. (X 6.) 

 Upper Helderberg group. JVear Le Roy, If. Y. 



'^'■"■'LlCHENALIA PEKMARGINATA. 



Page 82. 

 Fig. 30. An enlargement, showing the form and ari-angement of cell apertures. A single macula destitute 



of cells, and the larger cell a|)ertures immediately surrounding it. (X 6.) 

 -atmuq itilt fiiu, Upper Helderberg group. Onondaga Valley, N. Y. 



Lichenalia (PirtioTiiVrA) denticui.ata. 



Page 81. 

 See Plate 30. 

 Fig. 21. A specimen, natural size, incrusting a feiwutdla. 

 Fig. 22. An enlargenieut of a portion of the specimen, showing the form and arrangement of cell aj)erture8 



ami maoulaj of larg-er cells. (X 6.) 

 Fig. 27. An eidargement of a portion of the surface of a si)ecimeii, showing the cells nearly parallel with 

 the surface, ami macular destitute of cell apertures. The apertures contiguous to the macula; 

 indistinctly radiate from tbero. 



Upper Helderberg group. Falls of the UhUi river. 



Lichenalia subcava. 



Page 81. 

 Fig. 23. A specimen, natural size. 



Fig. 24. A natural section, showing the hollow spaces beneath the elevated niaculie. 



Fig. L'5. An enlargement of a jiortion of tig. 23, showing the form and arrangement of cell apertures, 

 and appearance of the elevated macule. 



Upper Helderberg gi-oup. EcUls of the Oltlo river. 



,i! ,. Lichenalia substellata. 



Page 78. 

 See Plate 30. 

 Fig. 26. An enlargement of a portion of the surface, showing the form and arrangement of cell apertures. 

 One of the sterile macula*, in the center uf the figure, shows the adjacent cell apertures larger 

 than the others and radiating from it. 



Upper Helderberg group. Falls of the Ohio river. 



