2IO 



THE GENUS AIONTICULIPORA. 



from six to ten lines in diameter, and from three or four to 

 seven or eight Hnes in height (fig. 45, a and b). Tangential 

 sections (fig. 45, c) show a close correspondence in general 

 structure with the type-form of M. Sehvynii, from the Trenton 

 Limestone. The corallum is composed of large and small 



''"'g- 45- — A> Upper view of a specimen oi MonticuUpora Sehvynii, var. Jiospitalis, Nich., from 

 the Cincinnati formation of Waynesville, Ohio, of the natural size : the coraUum is 

 attached by its base to the shell of Strophoniena nutans, James. K, Side view of the 

 same specimen, of the natural size, c, Tangential section of the same, enlarged eighteen 

 times. D, Vertical section of the same, enlarged eighteen times. 



corallites, the former being oval or circular in shape, and 

 varying from i-5oth to i-7oth inch in diameter, each showing 

 an excentrically perforated tabula. The small corallites are 

 numerous, sub-angular, and wedged in between all the larger 

 tubes, occasionally being aggregated into star-shaped groups 

 or " maculae." Besides the normal two kinds of corallites, a 

 considerable number of thick-walled hollow spines (" spiniform 

 corallites ") may be observed, which I have not detected as 

 present in the examples from the Trenton Limestone. 



Vertical sections (fig. 45, d) show the same marked differ- 

 ence in the tabulation of the large and small corallites as has 

 been previously noticed in the type-form, with some differ- 



