PLATE XXII—Continued. 
ICHTHYORACHIS NEREIS. 
Page 66. 
Fig-. 19. A fragment of a frond, natural size. 
Lower Helderberg group. Schoharie, N Y. 
Fig. 20. An enlargement of the specimen fig. 19. 
Fig, 21. An enlargement of the celluliferous side of another specimen. 
Synocladia ? sp. 
Fig. 22. The non-celluliferous face of a fragment of undetermined relations. 
Trematopora ? iinlet'. 
Fig. 23. A fragment, natural size. Introduced on this plate in error, and previously referred to the 
following species. 
Thamniscus ? ClSSEIS. 
Page 42. 
Fig. 24. A piece of rock with several fragments of the fossil on its surface. 
Fig. 25. This species associated, on a piece of rock, with other species of Bryozoa and Aulopora. 
Fig. 26. A branching frond, natural size. 
Fig. 27. A fragment enlarged ; the branch is twisted showing both the striate non-celluliferous side and a 
portion of the celluliferous surface. 
Fig. 28. An enlargement of the striated surface of a branch. 
Fig. 29. An enlargement of the celluliferous face of a branchlet, showing, in some parts, granulose cell 
margins, with some intermediate pustules or short spinules. 
Fig-. 30. The celluliferous face, partially worn, and with more circular apertures. 
Lower Helderberg group. Near Clarksville, N. Y. 
Thamniscus ? Nysa. 
Page 43. 
Figs. 31, 32. A branching fragment and an enlargement from the same. 
Fig. 47. A fragment, natural size. 
Fig. 48. An enlargement of the preceding. 
Lower Helderberg group. Clarksville, N. Y. 
Thamniscus fructicella. 
Page 42. 
Fig. 33. The non-celluliferous face of a branching- form. 
Thamniscus variolata. 
Page 41. 
Fig. 34. A portion of a frond, natural size. 
Fig. 35. A fragment showing- a striated surface with cells on the margins of the branchlets. 
Fig. 36. The celluliferous face of a larger frond. 
Fig. 37. The non-celluliferous face of an unusually large frond, showing cells on the margins of the 
branchlets. 
Fig. 38. The non-celluliferous side of a fragment with closely-crowded branchlets. 
Fig. 39. A fragment showing the smaller extremities of the branchlets. 
Figs. 40, 41. Two fragments showing the characters of the frond near its base. 
Fig. 42. A transverse section of a branch, showing numerous cellules. 
Fig. 43. An enlargement of the cell tubes, as seen looking upon the lateral margin of a branch. 
Fig. 44. An enlargement from the celluliferous face of a branch and branchlets, showing the irregular 
distribution of the cellules. 
Fig. 45. Aii enlargement from the specimen fig. 36, showing the celluliferous face and a part of the striated 
surface. 
Fig. 46. An enlargement of an irregularly-branching specimen, showing unequally distributed cell openings. 
Lower Helderberg group. Near Clarksville, N. Y. 
