PLATE XXXVII. 



Ch^TEI'ES FURCATUS 11. sp. 



Fig. 1. A fragment of a large branching specimen. 



Fig. 2. Two fragments from a larger brolien specimen imbedded in calcareous shale. 



Fig. 3. An enlargement of the cell-apertures as they appear upon the surface of fig. 1. 



Fig. 4. An enlargement of the cell-apertures from the specimen fig. 2. 



Fig. 5. A longitudinal section from a branch highly magnified, drawn from photographs and accu- 

 rately representing all that is visible in the section. Hamilton group, Norton's 

 Landing, Cayuga Lake, and other localities in Western New York. 



Ch^tetes tenuis n. sp. 



Fig. 6. The base of a hemispheric specimen, with a freshly fractured surface, showing the fine 

 columnar structure. 



Fig. 7. An enlargement from a polished portion of the upper part of the same, showing the forms 

 of the cells. 



Fig. 8. A vertical section, greatly enlarged, showing the cell-walls and distant diaphragms. 



Fig. 9. A vertical section of a similar form, where the cell-walls are thicker and the diaphragms 

 more numerous, while at a fevf points there are markings like mural pores. 



Fig. 10. A transverse section enlarged, showing the form and proportions of the cells (drawn 

 from a photograph.) Figs. 9 and 10 are referred with doubt to this species, until 

 farther studies shall determine their positive relations. Upper Helderberg Lime- 

 stone at Stafford, Genesee county, N. Y. 



Ch^TETES HUMILIS 11. sp. 



Fig. 11. A fragment of a hemispheric form, showing the fibro-columnar structure of the mass. 

 Fig. 12. An enlargement of several of the cells or columns, as they appear on the surface of the 



specimen fig. 11. 

 Fig. 13. An enlargement from a transverse section, to show the form and proportions of the cells. 

 Fig. 14. A longitudinal section, showing the cell-walls and transverse diaphragms. 

 Fig. 15. A longitudinal section of a fragment of the species, showing the cell-walls and diaphragms 



(drawn fi-om a photograph.) Upper Helderberg Limestone, Western New York. 



Ch^TETES TABULATUS 11. sp. 



Fig. 16. A vertical section of a subturbinate mass, showing the fibro-columnar structure. 

 Fig. 17. An enlargement of several of the columns from the surface of the specimen fig. 16. 

 Fig. 18. An enlargement of a tr.ansverse section, showing the form and proportions of the cells. 

 Fig. 19. A longitudinal section enlarged, shovv-ing the undulating vertical cell-walls without visible 



diaphragms. 

 This species belongs to the horizon of the Lower Helderberg group, and has been 



placed in this asisociation through accident. 



