Oh the Monticiilipotoid Corals of the Cineinnati Group, ij 



be considered niamnndata. M. molesta, Nich , seems to be nearly 

 the same externally, though it has a smaller number of interstitial 

 corallites. Infernally mainniulata has nearly straight tabulae, while 

 molcsta is said to have a series of vescicles on the sides of the walls 

 of the corallites. 



One of us has a specimen about nine inches across the longer 

 diameter, and five inches in the smaller. About four inches of the 

 longer diameter forms a dome-shaped mass, with an irregular sur- 

 face, covered with small, closely set monticules. Inside the speci- 

 men there are several branches running from the cap-like top 

 downwards, and spreading out into a wonderfully interlaced mass of 

 frondescent branches. The whole interior of the specimen is filled 

 with a mass of clay which surrounds the frondose branches on all 

 sides. 



Formation and Locality. — Lower Silurian, Cincinnati Group, 

 Cincinnati, O. 



38. — M. FRONDOSA. D'Orbigny. 



Prodr. de Paleont., I, 25, 1850. 



Chcstetes froiidosiis, Edw. & H., Pol. Foss. des Terr. Pal., 

 267, 1851, Nicholson, Quart. Jour. Geol. Soc, XXX, 508, 1874; 

 Pal. Ohio, II, 208, 1875; '^i''"- Nat. Hist., ser. 4. XVIII, 91, 

 1876. 



Cheetetes deeipiens, Rominger, Pro. Acad. Nat. Sci. Phila. , 116, 

 1866. 



Montictdipora {Peronopord) froiidosa, D'Orb., Nich., Genus 

 Montic, 216, 1881. 



Heterotrypa fro/hlflsa, D'Orb., LTlrich, Jour. Cin. S. Nat. Hist , 

 V. 235, 1882. 



Cheetetes eoii/pressus, Ulrich. Ibid, II, 27, 1S79. 



Peronopora eompressns, Ul. Ibid, V, 244, 1882. 



P. imiformis, Ul. Ibid, V, 244, 1882. 



dioiiiotrypa eurvata, Ul. Ibid, V, 242, 1882. 



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 

 circular, oval or sub-polygonal. These surrounded by a variable, 

 generally large number of smaller, irregularly shaped calices, occu- 

 pying the intervals between the preceding, and sometimes almost 

 surrounding them. Spiniform corallites numerous, placed on mar- 



