COKALS AND BrYOZOAXS OF THE LOWER HELDERBERG. 155 



Callopora Hyale. 



PLATE XII, PIGS. IS, 19.) 



Callopora Hyatt, Hall. Twenty-sixth Rep. N. Y. State Mus. Nat. Hist,, p. 100. 1874. 



Bryozouin ramose, branches hollow ; surface marked by comparatively large, 

 circular, or slightly oval cell-apertures w"hich are irregularly arranged, with fre- 

 quent macules destitute of cells. Intercellular spaces with small- shallow angu- 

 lar pits, sometimes three or four between the apertures. 



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

 Callopora venusta. 



(PLATE XII, FIGS. 20-24.) 



Cattopora venusta, Hall Twenty-sixth Rep. N.Y. State Mus. Nat. Hist., p. 101. 1874. 



Bryozoum ramose, hollow ; branches infrequent, widely diverging, from three 

 to seven mm. in diameter; thickness of bryozoum about .50 mm. ; cell-aper- 

 tures oval, about .20 mm. in length, width one-half the length ; distance from 

 each other generally equal to the width ; arranged in a more or less regular 

 quincunx order ; cell-margins elevated ; intercellular space channeled, having 

 generally a single series of angular pits, the margins of which are but slightly 

 elevated ; frequently they are so indistinct that the 'intercellular space presents 

 only a smooth, channeled appearance. There are occasional maculae destitute 

 of cells ; inner surface of the branches marked by strong, concentric wrinkles, 

 and by fine, longitudinal lines made by the recumbent portions of the cell-tubes. 



This species presents somewhat the appearance of C. cellulosa, but is easily 

 distinguished from that species by its oval cells, their closer and more regular 

 arrangement, the single series of intercellular pits and the hollow branches — 

 that species being solid. 



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



Callopora oculipera, n. sp. 



(PLATE XIII, FIG. 10.) 



Bryozoum ramose, solid ; diameter of branches one mm. ; cell-apertures 

 broadly oval; length about .30 mm., quite regularly arranged in longitudinal 

 rows, distant from each other less than the length of an aperture ; margins thin ; 

 the slightly elevated space between the apertures occupied by minute angular 

 pits, in one or two series, between adjacent apertures. 



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



