^ 



PLATE XI— Contiiincd. 



CaLLOPORA (CaLLOTRVPA) HETEROrORA. 



Page •&. 



See Plates 13 and 23. 



Kg. 32. An irreg^ilarly branching form, natural size. 



Lower Helderberg group. Clarksv'dle, N. X. 

 Fig. 33. A bifurcating branch, natural size. 



Lower Helderberg group. Clarkgville, N. Y. 

 Fig. 34. An enlargement, showing the surface characters, and the small oval cell apertures with iiiter- 

 apertural pita. 



Callopora (Callotrypa) unispina, HciU. 



I' age 'iO. 

 Fig. 35. A branching specimen, natural size. 



Lower Helderberg group. Clarksmlle, N. T. 

 Fig. 36. An enlargement, showing the surface character — a minute spine at the base of e.ach oval aperture 

 with one or two ranges of interapertural pits. 



Lower Helderberg group. Clarksville., N. Y. 

 Fig. 37. An enlargement, showing soim- of the cells with a minute spine, while it is absent fi-om othera. 

 Lower Helderberg gi-oup. Clarksville, N. Y. 



Callopora (Callotrypa) striata. 



Pugu iB. 



See Plate 23. 

 Fig. 38. A small fragment, natural raze. 



Lower Helderberg group. Schoharie, N. Y. 

 Fig. 39. An enlargement from the surface of the preceding, showing distant oval cell apertui-e-s the inter- 



a}>ertural pits elongate quadrang-ular, and this part of the surface striated. 

 Fig. 40. A piece of liraestoiie with gome small fragments distributed over the surface. 



Lower Helderberg group. ScholMrit, iV. Y. 

 Fig. 41. An enlargement, showing irregularly arranged oval i-cll apertures without spines at their base,_ 

 and the intermediate q>aces sti-iate, without being distinguished by pits. 



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