108 Twenty-sixth Report on the State Museum. 



Maculae distant from each other two to three times their own 

 diameter. Thickness of the frond two to three-hundredths of an 

 inch when single ; width in one specimen more than an inch and a 

 half. Seven to nine cells in one-tenth of an inch between the 

 maculae. 



This species resembles some of the so-called Chaetetes of the Hud- 

 son river formation of Cincinnati, Ohio. In the cell arrangement 

 and the maculae it may be compared with C. pavonia of D'Orb. ; but 

 the expansions are never so thick as in that one, though sometimes 

 occurring double. 



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

 Helderberg group, Schoharie, New York. 



Genus CEKAMOPOEA Rail. 

 Ceramopoka maculata n. sp. 



Brj.ozoum growing in thin disc-like expansions, incrusting shells 

 and other bodies, or free ; with a wrinkled epithecal crust beneath ; 

 flat or depressed on the upper side. Disc covered with larger and 

 smaller polygonal pores, the larger ones forming maculae at irregular 

 distances, and often formed by the union of two or three smaller 

 cells. The cells radiate from the center, their apertures directed 

 towards the margin of the disc, a little elongate, with the walls 

 slightly elevated at the angles, forming angular projections. In 

 small specimens the apertures are more elongate ; and in the very 

 young condition, where the cells are just forming on surfaces, they 

 are extremely elongate with the posterior portion of the aperture 

 hooded, and having an indistinct radiation from each of the maculae. 

 This character becomes obscured in older specimens from the bend- 

 ing upwards of the cells in the process of growth. 



Discs from one-fourth of an inch to one inch and a half, or more, 

 in diameter ; the thickness in larger specimens an eighth of an inch. 

 Between the maculae about five cells occupy a tenth of an inch. 



This species resembles O. imhricata of the Niagara limestone, but 

 differs in the less distinctly hooded apertures, the maculae more 

 obscure and less strongly divided and radiate, and it also grows much 

 larger. 



Formation and locality. — In shaly limestones of the Lower Hel- 

 derberg group, near Clarksville, Albany county, and at Schoharie, 

 New York. 



