1 882.] The Paleontologist. 47 



are horizontal, but in some they take an oblique or bent course across 

 the corallites. 



Some specimens found associated with this exhibit a sligJit tendency 

 to forming " monticules," but in other respects they seem identical. 



In outline and habit of growth this resembles M. sp. discoidea, James, 

 but in other respects it is materially different, particularly the interior 

 structure. 



Found by the writer in the upper beds of the Cincinnati Group, 

 Clinton and Warren counties, Ohio. 



MoNTicuLiPORA {Hctei otrypo) o'nealli ? var. communis. James. 



Corallum, as generally found, much broken, cylindrical or subcylin- 

 drical stems from one to three lines in diameter, branching at variable 

 distances in different directions at acute angles, but masses of consider- 

 able size — from one inch to six or eight inches or more in diameter — 

 are sometimes found, in which the stems anastomose frequently in a ver)^ 

 irregular manner. Most specimens exhibit maculae or "monticules," 

 raised very little or none at all above the general surface, occupied by 

 calices much larger than the average, and sometimes clusters of the 

 smaller tubules. Calices generally oval or subcircular, occasionally 

 somewhat angular; interstitial tubuli numerous, sometimes nearly or 

 quite surrounding the larger cells, and of various shapes : an average of 

 about six calices in the space of one line in the longitudinal direction of 

 the stem, and seven or eight transversely. Apertures of cell walls thin 

 at the surface of unworn specimens, but thickened immediately below, 

 as shown by abraded examples, mostly found in that condition. 



In tangential section the cells are oval or subcircular, walls much 

 thickened and distinctly defined by a dividing space, interstitial tubuli 

 circular or angular. Section of a cylindrical stem, cut longitudinally, 

 shows the corallites as very thin walled centrally, and taking a longitud- 

 inal direction with a very slight outward inclination till near the surface, 

 where they make a decided curve and open obliquely. Tabulre remote 

 in the axial part, none observed in the space of one fourth of an inch in 

 the example used for this description, but near the surface they become 

 distinct, in some cases depressed or bent downward in the middle, or 

 taking an oblique direction across the corallites ; the smaller tubes are 

 more closely tabulate. In a transverse section of the axial portion the 

 tubes are thin walled, circular or angular, and occupied by cruciform dis- 

 sepiments, the interstitial pores variable in shape. 



The interior structure of this species bears quite a close resemblance 

 to M. sp. o'nealli, James, but the exterior differs materially, in being of 

 a much more robust habit, in the macule of larger calices, and groups of 

 small pores. It is considered, by some, to be M. (Chfetetes) sp. ap- 

 proximata, Nicholson, but, clearly, it is not the form described and 

 figured by Prof. N. as appoxiniatus in the 2d vol. of Ohio Paleontology, 

 1875, and again in his valuable work on '• Monticulipora," 188 1, where 



