74 
BULLETIN OF THE LABORATORIES 
distribution we are accustomed to look for variations, and our speci- 
mens are probably the smaller sized form of the same. 
Flint Ridge and Bald Hill. Rather common. 
III. Rhombopora . 
{Plate VII, Fig, 5, b, c.) . 
A fragment showing the same internal features as the last probably 
belongs to the same species. About 6 cells are found in a distance of 
2 mm. in- the longitudinal series, and about 8 cells in the same dis- 
tance in the diagonal series. The apertures are decidedly rhomboid, 
the ridges bear rounded nodes at their intersections and show faint 
traces of low granules between the cells. They recall strongly Meek^s 
figures of the type specimens. They seem to us to owe their more de- 
cidedly rhomboid character partly to the elfects of exfoliation of the 
outer crust. 
CYSTODICTYONID/E, Ulrich. 
Frond composed of two or more layers of cells, united along their 
epithecal membranes. Tubular cells with vertical folds or indenta- 
tions, the remains of the crescent shaped lip. Interstitial spaces oc- 
cupied by vesicular tissue, not visible at the surface. 
Genus CYSTODICTYA, Ulrich. 
Frond composed of two cell layers, branches compressed, divid- 
ing dichotomously, with sharp, nonporiferous margins. Cells arranged 
in diagonal intersecting series, with more or less marked longitudinal 
series. Interstitial cells arranged in longitudinal series, angular; ar- 
rangement more or less disturbed about the cells. 
IV. Cystodictya carbonaria, Meek. 
{Plate VII, Fig. 2, a, A c) 
Plilodictya (Stictopora) carbonaria, Meek ; Proc. Acad. Nat. Sci. Phil. 
XXIII., p. 16); Ohio Pal. Vol. II, p. 328. 
Fronds dividing dichotomously at intervals from 5 to 15 mm, 
branches very thin, non-poriferous margin narrow, smooth, or rarely 
with faint striations. Branches 4 to 4. 7 mm. wide, with 9 to ii longi- 
tudinal rows of cells. Cells arranged in diagonal intersecting rows, 
more or less curved laterally and sometimes separated there by faint 
grooves. Single undulating striations more less irregular extend 
