114 PALAEONTOLOGY OF OHIO. 



general resemblance is much the same, but these differences distinguish 

 it quite readily. 



Formation and locality; In the limestones of the Clinton group, at the Soldiers' 

 Home, near Dayton, Ohio. 



Genus PH^NOPORA, HhII, 1852. 



(Pal. N. Y., Vol. IL, p. 46.} 



Ph^nopoea (Ptilodictya) expansa (n. sp.). 



Plate 6, flg. 1. 



Frond forming broad, elongate stipes, the entire length and form not 

 determined, the larger fragments seen measuring nearly an inch in 

 width, by nearly two and three-quarter inches in length, with a thick- 

 ness of an eighth of an inch. The lateral edges are slightly irregular, 

 but generally parallel in the specimens under consideration. Frond dis- 

 tinctly separated longitudinally into two parts by a thin, central parti- 

 tion extending from edge to edge, from the surfaces of which the cells 

 take their origin, and diverge obliquely upward and outward to the 

 surface of the frond. 



Surface of the frond divided by thin," longitudinal partitions, forming 

 the sides of the cells, and separating them into longitudinal rows. The 

 •outer edges of the partitions are slightly raised above the upper and 

 lower walls of the cells, and count ten or eleven in the space of a tenth 

 of an inch. Cells slightly oval, a little longer than wide, arranged in 

 horizontal, or nearly horizontal, rows, diverging from the central parti- 

 tion at an angle of about fifteen degrees above a horizontal, but varying 

 somewhat in different parts of the frond. There is an appearance of 

 maculae, or slightly elevated patches, on the surface, but they are not 

 sufiieiently distinct to determine their order or arrangement. 



The species is of the type and somewhat resembles P. constellata, Hall, 

 from the Clinton group of New York, but the fronds are larger and 

 thicker, while the maculae of the surface are much less distinct. It is 

 possible, however, that if compared with more perfect specimens than 

 we have seen, that it may prove to be more nearly allied than we have 

 supposed. 



Formation and locality : In the limestones of the Clinton group, near Dayton, Ohio. 



