CORALS AND BRYOZOA. 
99 
PHRACTOPORA, Hall. 1881. 
PlIRACTOPORA CRISTATA. 
PLATE XXXI, FIGS. 36, 37. 
Phractopora cristata, Hall. Trans. Albany Institute, vol. x, abstract, p. 12. 1881. 
“ “ Report of State Geologist for 1885. Expl. pi. 31, figs. 36, 37. 1887. 
Zoarium consisting of explanate fronds, celluliferous on one or both faces, 
free or incrusting other objects. The surface is raised at irregular intervals 
into elevated crests, which are celluliferous on each face, sometimes attaining 
a height of 5 mm. or more. Cells tubular, arising from a mesotheca, oblique 
to the surface ; septa wanting. Apertures sub-circular, oblique, diameter .30 
mm.; closely disposed, usually in diagonally intersecting rows. Peristomes 
thin, posterior portion strongly elevated, projecting over and constricting 
the opening. The maculae consist of circular spaces, 1 mm. in diameter, 
destitute of cell apertures, and occurring at intervals of about 4 mm. The 
apertures adjacent to these do not radiate from them. Intercellular struc¬ 
ture, near the base, irregularly vesiculose, becoming regularly septate above. 
On a portion of one frond the cell apertures are smaller, crescentic, and 
denticulated, presenting a very different appearance from the ordinary 
condition. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Phractopora cristata, var. lineata. 
PLATE XXXI, FIGS. 31, 33. 
Phractopora cristata, var. lineata. Report of State Geologist for 1885. Expl. pi. 31, figs. 34, 35. 1887. 
In this form the crests are not prominent; frequently the surface is traversed 
by narrow, slightly elevated carinoe. The cell apertures are more nearly cir¬ 
cular, less oblique, and the margins more equally elevated than in P. cristata 
proper. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
