The Paleontologist. [July 2, 



GENUS PTILODICTYA, (Lonsdale) 



Ptilodictya Hilli- (James.) Polyzoary an unbranched, elongated, flattened, two- 

 edged frond. Transverse section acutely elliptical, a little more than a line in thickness 

 in the middle ; faces of the frond gently curved to the thin sharp edges. Central axis 

 clearly sRown, both faces celluliferous. Prominent transverse, parallel ridges cross and 

 extend over the whole length of the frond, about one line apart, giving it a corrugated 

 appearance — a marked feature of the species. Cell apertures oval or lozenge-shaped, 

 arranged between two series of elevated lines crossing the frond obliquely from the op- 

 posite edges. About eight cell apertures in the space of a line, measuring diagonally, not 

 interrupted in their regularity in passing over the ridges. The cells seem to extend to the 

 thin edges of the frond, but as the examples examined are somewhat weathered on the 

 edges it is difficult to determine this point positively. 



The two specimens examined are lying on opposite surfaces of a small block of lime- 

 stone. One of them two and a half inches long, and six lines broad the whole length ; 

 the other is one and a half inch long and about four and a half lines broad to within six 

 lines of the base, where it slopes oft' abruptly from one side, wedge-shaped to an acute 

 point, the other side continues straight to the pointed end. It is not certain that this 

 pointed base (?) is the normal form of the species, it may have been caused by weather- 

 ing but it does not so appear. 



The marked and decided dift'erence between this species and P.falciformis, Nicholson, 

 is the promi7ient transverse Hdges. 



Named in honor of Dr. H. H. Hill, of Cincinnati, who found the specimens on the 

 bank of the Ohio River at Cincinnati. 



Ptilodictya plumaria. (James.) Polyzoary plumose, pointed at the base, divided 

 into three lobe-like parts by longitudinal depressions commencing near the base, which 

 flatten out gradually as they approach the upper part, with a row of elongated, oblique 

 pits in each depression directed outward and upward ; the lower part of the central lobe 

 gently curving from the base upward to about half the length of the specimen ; the lat- 

 eral lobes expand quite rapidly, and to thin edges — one side at a sharper angle than the 

 other. On the surface are several rows of slightly radiating low nodes. Quite strong 

 longitudinal wavy lines on the central lobe, from eight to ten in the space of a line, be- 

 tween which, measuring in the same direction, are about ten circular or oval cell apertures 

 in the space of a line. The cells on the lateral lobes are quite indistinct on the only speci- 

 men yet examined, caused by weathering. A small portion of the upper part is covered 

 with rock ; the exposed part measures one and three-quarter inches in length, and seven- 

 eigths of an inch in width at the broadest part. 



I am indebted to G. T. O'Neall, Esq., of Waynesville, Warren Co., O., for this beauti- 

 ful specimen, who found it near that place — upper part of the Cincinnati group. 



Ptilodictya flexUOSa- (James.) Polyzoary consisting of small, thin, flexuous 

 fronds about two-thirds of a line in width, with sharp edges, giving oft' lateral branches 

 about half the width of the main stem about two and a half lines apart ; transverse section 

 flat oval ; the main stem curving slightly opposite and just above each branch. Six or 

 eight rows of alternating, oval cell apertures on the main frond, and about half as many 

 on the branches; about four cells in the space of a line measuring longitudinally. One 

 row of cells on each side have an oblique direction ; close on the edge of the frond, out- 

 side of the oblique row, is a row of imperfect cell mouths about half the width of the 

 others. On some parts'of the frond the cell walls are in contact, on other parts they are 

 separate with minute tubuli between of very irregular forms. 



This species bears some resemblance to P. Shafferi, Meek, but differs materially in being 

 destitute of the sinuous longitudinal lines between the cells, the form of the apertures, the 

 outer imperfect row of cells and the lateral branches. 



Locality — Cincinnati. 



Ptilodictya granulosa. (James). Polyzoary consisting of flattened two-edged 

 fronds; branching dichotomously celluliferous on both faces; about one line in width ; the 

 main frond and branches nearly equal. Length not known. Transverse section com- 

 pressed elliptical, one-quarter of a line or less in thickness through the center. Surface 

 entirely covered with exceedingly \\-\\w\x\.^ gra miles not visible to the naked eye, but quite 

 conspicuous under a good lens. From eight to eleven alternating rows of cells arranged 

 between longitudinal lines in a quincuncial manner, the outer row on each edge has an 

 oblique upward direction. Cell apertures elliptical, about five in the space of a line lon- 

 gitudinally. 



Locality — Cincinnati. 



