CORALS AND BRYOZOA. 25 



contact with adjacent apertures: margins distinctly and equally elevated, 

 occasionally nodose. Mesopores minute: margins of the same height as 

 those of the apertures. No internal vesicular structure visible. 



Formatim and localities. In tlie shaly limestone of the Lower Helderberg 

 group, at Catskill, Greene county; near Clarksville, and at Schoharie, N. Y. 



Callopora (Calloteypa) macropora, var. signata. 



PLATE XI, FKJS. M, 31. 



Trematopota sUfiuUa, Hall. Twenty-sixth Rept. N. Y. State Mils. Nat. Hist., p. 104. 1874. 

 CiUUtpni-a iiMcritpttra, vai-. xiguula. Hall. Thii-ty-secoiul Rept. N. Y. State Mius. Nat. Hist., p. l.")3. 1879. 



Report of State Geologist for 18S2. Kxpl. pi. 1 1, figs. 80, 31. 

 1883. 



This variety differs from the usual form of C. macropora in the more distinctly 

 polygonal cell apertures, and in having but very few intercelhilar pits. 

 Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 



Callopora (Callotrypa) heteropora. 



PLATE XI, VVii. 3i-3l ; PLATE XIII, FIGS. 6-8 ; AND PLATE XXIH, FIG. S. 



Callopora heteropora. Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 102. 1874. 



ITiirty-second Rept. N. Y. State Mus. Nat. Hist., p. 153. 1879. 

 " •• " Report of State Geologist for 1882. Expl. pi. 11, figs. 32-34; pi. 13, figs. 5-8. 



1883. 



ZoARiUM ramose, solid, diameter of branches from 1 to 1.50 mm.; bifurcations 

 distant; branches diverging at an angle of forty-five degrees. Cells tubular, 

 arising from the center of the brancli and very gradually diverging till within 

 a short distance of the surface, when they turn abruptly outward ; at this point 

 the walls, previously very thin, become thicker, slightly constricting the cell. 

 For the greater portion of their length the cells are in contact and sub- 

 angular from mutual pressure. Apertures oval, length .20 mm., width about 

 two-thirds the lengtli ; irregularly disposed : margins equally elevated. 

 Me.sopores minute, elongate, angular, so arranged that their margins often 



