602 



Beport of the State G-eologist. 



walls thin ; apertures broadly elliptical, surrounded by a narrow 

 sloping area, hexagonal in outline. When perfect there is a 

 depressed calcareous plate that closes nearly two-thirds of the 

 aperture, the orifice left being subtriangular in form. With age, 

 successive layers are developed directly over the first, so that 

 they gradually form a cell tube, seemingly having the cavity 

 intersected by incomplete diaphragms, which appear to have 

 their origin on the posterior wall, and extend out half way 

 across." 



214 



216 



215 



Fig. 214. Proutelladiscoidea. Under surface, natural size. 

 Fig. 215. Upper surface of a fragment, natural size. 

 Fig. 216. A portion of the surface, x 9. 



Family Worthenoporidae, Ulrich. 

 This family includes at present only the genus Wobthenopora. 



WoETHENOPORA, Ulrich. 

 (Geol. Sur. 111., Yol. YIII, p. 403. 1890.) 

 Type, Worthenojpora spinosa, Ulrich. 



"Zoarium bifoliate, branching or palmate. Cells very regu- 

 larly arranged, subtubular, with the apertures semielliptical. 

 On the surface the line of junction between the cells is marked 

 by a longitudinal, elevated ridge. The truncate posterior margin 

 of the aperture is raised into a less strong transverse bar. The 

 elongate, triangular depressed front appears perfectly plain." 



The condition in which the three following genera occur render 

 their classification difiicult: Ascodiotyon, Rhopalonaria and 



YiNELLA. 



