26 PALEONTOLOGY OF NEW YORK. 



resemble fine striations. The margins of the apertures and intermediate pits 

 are frequently spinulose. 



Formation and locality. In the shaly limestone of the Lower Helderberg 

 group, near Clarksville, Albany county, N. Y. 



Callopoba (Callotrypa) unispina. 



PLATE XI, KIGS 35-;)7. 



CaUapora uuixpina. Hall. Tweiity-tiixlh Rept. N. Y. State Mas. Nat. Hist., p. 102. 1874. 

 " " " Thii-ty-second Rept. N. Y. State Mns. Nat. Hist., p. 153. 1879. 



In i>»rt Callopora unigpina. Hall. Report of State Geologist for 1882. Expl. pi. 11, figs. 3.")-4l. I88S. 



ZoARiUH ramose, solid, diameter from 1.50 to 2 mm. Cells tubular, arising 

 from the center of the branch and regularly curving to the surface. Aper- 

 tures broadly oval, length .17 mm., width about three-fourths the length; 

 occasionally circular, closely and irregularly disposed : margins moderately 

 strong, equally elevated. At the base of each aperture is a, comparatively, 

 very prominent spinule. Mesopores minute, elongate, angular, so disposed 

 that the margins give to the surface a finely striated appearance. No vesi- 

 cular intercellular space. 



This species, when well preserved, will be easily recognized by the prominent 

 spinule at the base of each aperture ; when worn or macerated it very closely 

 resembles C. heteropora. 



Formation and localities. In the shaly limestone of the Lower Helderberg 

 group, on Catskill creek, Greene county, and near Clarksville, Albany county, 

 N. Y. 



Callopora (Callotrypa) striata, n. sp. 



PLATS XI, FIGS. 88-41 ; AND PLATE XXIH, FIGS. 13, U. 



In part Callopora wiitpina. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. Ui3. 1880. 



Report of State Geologist for 1882. Expl. pi. II, figs. 35-11. 1883. 



ZoARiUM ramose, solid, diameter of branches 1 mm. ; bifurcations infrequent. 

 Cell apertures oval, length .33 mm., width about one-half the length; 

 irregularly disposed, sometimes in contact; at other times distant .33 mm. 

 or more : margins moderately strong, distinctly and equally elevated. At 



