PLATE IX. 

 Ch.«;tete8 (Monotrypella) arbusculus. 



l*Ug« 12. 



A branching specimen on a fragment of limestone, natural size. 



Tentaciilite limestone. Schoharie, N. T. 

 A separate branching specimen, natural size. 



Tentaculite limestone. 8choharie, N. ¥. 

 The base of a group of the same character as fig. 2. 



Tentaculite limestone. Schoharie, N. Y. 

 A fragment, natural size, showing a peculiar mode of growth, and referred to this species with 

 doubt. 



Tentaculite limestone. Schoharie, N. Y. 

 Fragments of branching forms, natural size, apparently of the same species as fig. 4. 



Tentaculite limestone. Schoharie, N. Y. 

 An enlargement from the surface of fig. 5, showing the character of the branches and the cell 



openings. 

 An enlargement from fig. 1, showing cell apertui"es and form of the columns from the cell filling. 

 A branching specimen, somewhat more slender than the prevailing fonns. 



Lower Helderberg g^oup. Schoharie, N. Y. 



CHiKTKTES (Mo.VOTRYPELLa) ABRUFIU.S. 

 Pago 13. 

 Fig. 9. An irregularly branching specimen which is weathered or broken so as to show the columns. 



Lower Pentamerus limestone. Schnharie, N. Y 

 Fig. 10. An enlargement from the preceding, showing the surface characters and cell apertures. 

 Fig. 11. A translucent section, enlarged, from the base of a bifurcation, showing the charactei-s of the 

 cells, which in the center are nearly or quite free fi-om septa, turning rapidly outward and 

 becoming frequently septate as they approach the surface. 



Ptychone.ma tabulatum. 



Page 14. 

 Fig. 12. A vertical section of a hemispheric mass showing the columns with corrugated sides. 

 Fig. 13. An enlai-gement of a portion showing the peculiar corrugated surfaces of the columns. 

 Fig. 14. An enlargement of a vertical translucent section showing the undulated cell walls. 

 Fig. 15. A transverse section showing the form of the cells. (X 6). 



PtYCHONEMA HBLDERBBROIiS. 



Page 16. 

 Fig. 16. A portion of a branching form presenting the same character of cell walls as the preceding. 

 Fig. 17. An enlargement of the sui-face showing the form of the cell apertures. 



