2 2 Cincinnati Society of Natural History. 



43. — M. okToNi, Nicholson. 



Monticulipom (/) ortoui, Nich. Whitfield Geol. of Wise. IV, 

 251, 1882. 



M. [J^eronopora) ortoiii, Nich. Genus Montic. 228, 1881. 



Cluetctes ortoni, Nich. Quar. jour Geol. Soc. XXX, 513, 

 1874; Pal. Ohio, II, 211, 1875. 



Atactflpofa o?toni, Ulrich. Cat. P'os. Gin. Gr. , 13, i88o: jour. 

 Gin. S. Nat. Hist., II, 120, 1879; VI, 246, 1883. 



AtactoporcUa ortoni, Ul. Ibid, VI, 248, 253, 256, 1883. 



Atactopora iiiultii^raiwsa, Ul. Ibid, II, 122, 1879. 



AtactoporcUa iiiultigranosa, V\. Ibid, VI, 254, 1883. 



Atactopora iiii/ndiila, V\. Ibid, 11, 123, 1879. 



A. tcnella, Ul. Ibid, II, 123, 1873. 



AtactoporcUa niuiidula, Ld. ll)id, VI, 252, 1883. 



A. schuchcrti. Id. Ibid, VI, 251, 1883. 



Corallum forming a very thin crust parasitic on shells of Ortho- 

 ceras, Strophoinena, and fronds of various corals, varying from one- 

 ninth to three fourths of a line thick, and rarely more than one inch 

 in diameter. Surface with numerous rounded or conical monti- 

 cules, more or less regularly distributed, from one-half a line to a 

 line or more apart, and either solid or bearing calices of the ordin- 

 ary size. Calices irregular in shape, often indented by one or more 

 tooth like or blunt projections; margins varying in different exam- 

 ples from thin to very thick, and generally studded with small tub- 

 ercles, giving the surface a granular appearance. Interstitial cells 

 more or less numerous. 



Obs. — The various forms of this species do not seem to pre- 

 sent sufficient difference to justify regarding them as distinct species. 

 One {A. }iiuIti^^ranos.a) has a thicker corallum than ordinary, and 

 groups of larger sized tubes. In A. mundula the original descrip- 

 tion st.ites that the walls are thick, the amended one (under Atacto- 

 porcUa) calls them thin. Lastly, A. schuchcrti differs in having more 

 prominent spiniform corallites. All these are small differences. 

 The species can be mainly recognized by its limited extent, the 

 regular arrangement of the rounded monticules, and the indented 

 calices. 



Formation and Locality. — Lower Silurian, Cincinnati Group, 

 Cincinnati, Oxford, Ohio, etc. Hudson River Group of New 

 York Delafield, Wise. 



44. — M. PAPiLLAT.\, McCoy. 



Edw. & Haine, Brit. Foss. Cor., p. 266, 1850. 



