38 Cincinnati Society of Natural History. 



irregular, slightly oblique. 'I'hree cells to a line longitudinally, 

 four or five transversely. 



Obs. This differs from the preceding in the larger size of the 

 cells, and the less regular arrangement. It seems to be almost 

 invariably found on Orthoceras. 



Formation and Locality. Lower Silurian, Cin'ti Or., Warren 

 Co., Ohio. 



3. C. CONCENTRICA, U. P. James. The Palaeontologist, p. 

 5, 1878. 



Corallum formimg simple crusts, or cylindrical or flattened 

 branches, two to five lines in diameter, made up of concentric 

 layers, each one-quarter to one-half a line thick : the incrusting 

 forms growing on crinoid stems or other substances. Surface 

 generally with maculae, two lines apart from centre to centre, 

 occupied by from four to six tubes, spreading in different direc- 

 tions. Calices circular or oval, often arranged in short alternating 

 series. Apertures raised and arched. Walls rather thick, the 

 margins often raised and thin and sharp. In worn specimens 

 interstitial cells are shown. (Plate i. Figs. 8, 8 a). 



Obs. Thsi species may generally be recognized by the regular 

 arrangement of the cell apertures, which spread in all directions 

 generally from the centre of one of the maculre. It somewhat 

 resembles in this respect MonticiiUpora rcctaugularis, Whitf. , from 

 Wisconsin, but differs from that in the circular or oval cells. 



Formation and Locality. Lower Silurian, Cin'ti Group, Cin- 

 cinnati, O. 



4. C. (?) wHiTEi. U. P. James. 

 The Palgeontol. (without ?) p. 12, 1878. 



Corallum incrusting various objects, generally corals, forming 

 masses three by six inches, more or less. Surface with slightly 

 elevated areolae, these cells smaller than the general average. 

 Calices circular or oval to triangular, &:c., varying also in size. 

 Apertures slightly elevated and oblique, but mostly direct. Walls 

 very thin. A few interstitial cells between some of the larger 

 cells. (Plate i. Figs. 9, 9^.) 



Obs. — This form is placed in the genus Ceramopoi a provision- 

 ally only. It presents many features of a typical AioiiticHlipora, 

 and perhaps should be placed there, 'i'he clusters of smaller cells 

 together with the thin walls seem chiefly to distinguish it. 



Formation and Locality. — Lower Silurian, Cincinnati Groups, 

 Cincinnati, O. 



