72 



Cincinnati Society of Natural History. 



macular j interstitial spaces sometimes smooth and apparently solid (in 

 worn specimens) : sometimes with small interstitial cells, and again 

 (in the best preserved specimens), with numbers of spines or granules 

 on the walls of the interstitial cells ; corallites in the axial region with 

 moderately thin and flexuous walls, thickening toward the surface; 

 sub-angular or nearly circular and in contact at limited points, the 

 intervening spaces occupied by smaller and angular interstitial cells ; 

 spiniform tubuli, if any, small and inconspicuous ; in the mature 

 region interstitial cells seemingly suppressed by the spiniform tubuli, 

 which are arranged in one or two crowded series ; tabulae usually 

 wanting in the large corallites in the axial region and not numerous 

 elsewhere ; in the interstitial cells numerous and closely set. (Jour. 

 Cin. Soc. Nat. Hist. vol. 6, 1883, p. 85, as Heterotrypa vanpeli. 

 Placed in the new genus Nicholsonella'm Geol. Sur. Ills., vol. 8, 1890, 

 p. 421.) 



Locality. — Cincinnati and Waynesville, Ohio. 



48. — M. pustulosa Ulrich (sp.), 1890. 



( orallum sub-ramose or irregularly compressed, averaging eight 

 mm. thick; surface generally with low monticules, about 2.6 mm. 

 apart, consisting of groups of larger cells with a few small ones; 

 corallites slightly flexuous, somewhat thickened in the cortical region, 

 polygonal, hexagonal and pentagonal, nine in two mm.; calices sub- 

 polygonal, one-half larger in the monticules than elsewhere ; in the 

 axial region tabulae twice, their diameter apart, becoming more numer- 

 ous toward the periphery; spiniform corallites fairly numerous, 

 commonly situated at the angles. (Geol. Sur. Ills., vol. 8, 1890, p. 

 451, as Amplexopora pustulosa.) 



Locality. — Hanover, Clarksville, and other places in Ohio. 



49. — M. frondosa D'Orb., 1850. 



Corallum of erect, flattened, undulating expansions of variable 

 height, and varying from less than one to four lines thick ; surface 

 with numerous rounded or stellate spaces, either elevated to form 

 monticules, or level with the general surface, and composed mainly of 

 small tubuli ; larger calices moderately thick walled, irregularly circu- 

 lar, oval or sub-polygonal; these surrounded by a variable, generally 

 large number of smaller, irregularly shaped calices, occupying the 

 intervals between the preceding, and sometimes almost surrounding 



