4-6 The PaleontologiU. \Sept. 12, 



tangential the cells become somewhat more regular in shape, approaching 

 to oval or subcircular, and still lower, just above the abrupt curve, they 

 are still more regular in outline ; the small circular cells at the angles of 

 the corallites are shown more or less numerous in the three last named 

 transverse sections. 



The tangential section, and perhaps the central part of this species, 

 resembles M sp, iuiplicata, Ulrich, as described and figured by Prof. 

 Nicholson ("Moticulipora," p. 147), but in other features it differs widely ; 

 particularly in the mode of growth, the surface markings, and especially 

 the tabulation of the tubes after leaving the central part. 



The example used, principally^ for this description, is one of the 

 expanded, flattened forms. 



The writer found 47 fragments of this species that he has reason for 

 believing were parts of one corallum, being all within an area of about 

 15 inches in diameter. No attempt has been made at restoration, as it 

 is hardly possible that all the fragments were collected, being mingled 

 with a mass of clay. 



Locality — Upper part of the Cincinnati Group, Clinton Co., O. 



MoNTicuLiPORA {Heterotrypa) circularis, sp. nov. James. 



Corallum, concavo convex ; the concavity of the base corresponding 

 with the convex upper surface, causing an even thickness of from less 

 than half aline to about one line in different specimens ; size, varying from 

 one fourth of an inch to one inch in diameter ; circular in outline ; surface, 

 even and destitute of "monticules," or groups of larger calices than the 

 average ; apertures of cells of unworn specimens, sharp, but they are 

 seldom found in that condition, nearly all, as far as observed, being more 

 or less abraded, showing the cell walls as much thickened ; calices, sub- 

 circular, or somewhat angular in some cases, uniform in size, seven or 

 eight in the space of one line, sometimes arranged in regular, slightly 

 curved rows of from 4 to 12 or more; no minute tube apertures ob- 

 served. The concave base of unworn examples is covered with a very 

 thin, delicate epitheca. showing very fine concentric lines, and radiating 

 striae, worn ones show the bases of the corallites. Specimens 

 partly embedded in the surface of rocks are as often found base upward 

 as downward ; detached specimens are not uncommon, all indicating the 

 free habit of the species. 



Sections of the interior show two series of tubes, a larger and a smaller, 

 the larger, only, being noticeable at the surface. In tangential section 

 the larger tubes are mostly circular with distinct borders ; the smaller, 

 which surround the others in some cases, are the most numerous, and 

 vary greatly in shape. In a transverse section, taken just above the 

 base the larger tubes seem to be slightly expanded, and the smaller not 

 occupying so much space, otherwise it is very much like the tangential 

 section. In vertical section the tubes take a somewhat bent or tortuous 

 course, and are tabulate from the base to the upper surface, the smaller 

 ones generally more closely than the larger. In most cases, the tabulae 



