Genera of the ISTorth American Palaeozoic Bryozoa. 593 



bodies by their under surface, which consists of a concentrically 

 wrinkled epitheca. Nearly all the specimens observed are para- 

 sitic on Cyathophylloid or Favositoid corals, sometimes occurring 

 in groups of from seventy-five to a hundred zoaria. 



Zoarium convex with a depressed central area, which is some- 

 what variable in size. 



Cells tubular, rectangular to the surface, disposed in double 

 radiating rows, extending above the surface and forming promi- 

 nent ridges ; adjacent ridges generally separated by a space 

 about equal to the width of a ridge, but sometimes more closely 

 disposed. Alternate ridges extend from the depressed central 

 space to the margin, the others commencing at about one-half 

 the distance to the margin ; cell apertures circular, in contact, 

 often inosculating, having the appearance of being immersed ; 

 intercellular space vesiculose; vesicles comparatively large and 

 irregularly disposed. The concave central space, that between 

 the ridges and between the zoaria is vesicular, the vesicles 

 between the ridges being much smaller than those occupying the 

 central space. Between the zoaria some of the vesicles are of 

 the same size as those between the ridges, others are much larger, 

 circular or polygonal from mutual pressure. 



Scenellopora, IJlrich. 

 (Jour. Cin. Soc. Nat. Hist., p. 150. 1882.) 

 Type, Scenellopora radiata^ Ulrich. 



Zoarium obconical the under side with an epitheca ; the upper 

 slightly concave and celluliferous ; cell apertures occupying the 

 cfenter of ridges which radiate from a subsolid and depressed, 

 center ; intermediate space smooth, without cells. 



Fig. 194. Scenellopora radiata. Profile and top view, natural 

 Fig. 195. A portion of the uoncelluliferous surface, x8. 



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