272 
PALEONTOLOGY OF NEW YORK. 
Ptilodictya retiformis, n. sp. 
PLATE LXI, FIG. 13. 
This species, in its manner of growth and general appearance, is very similar 
to P. plumea, but the cell apertures are more nearly oval, and more closely dis¬ 
posed. The interapertural space is angular, minutely granulose, and with a 
prominent node at each cell angle. The surface is not marked by maculae or 
monticules. It may be distinguished from P. scutulata, which it closely resem¬ 
bles in its surface characters, by its much wider frond. 
Formation and locality. Hamilton group, Alden, Erie county, N. Y. 
Ptilodictya scutulata. 
NOT FIGURED. 
Stictopora ? scutulata, Hall. Trans. Albany Institute, vol. x, p. 191. 1881. 
“ “ “ Report of State Geologist for 1883, p. 47. 1S84. 
Zoarium consisting of a flattened frond, width from 1.50 to 2.50 mm.; without 
non-celluliferous marginal space. Transverse section lenticular, greatest 
thickness .25 mm.; marginal angles not acute. Cells tubular, arising from a 
mesotheca. Cell apertures oval, length .20 mm., width two-thirds the length, 
closely disposed, nearly in contact, sometimes irregularly disposed, at other 
times forming oblique intersecting rows. The interapertural space is elevated, 
angulated, having a line of minute nodes or granules, and frequently 
more prominent nodes at the angles. The surface presents a reticulated 
appearance. 
Since no bifurcations have been observed, and as specimens more than 20 
mm. in length occur without branches, it seems sufficient evidence to remove 
it from Stictopora to which it was originally referred. The cell apertures 
resemble those of Ptilodictya retiformis, hut the species may be distinguished 
by its much narrower form. It has precisely the ajipearance of a flattened 
frond of some specie, of Orthopoiia, but the mesotheca and manner of growth 
of the cell tubes show its alliance with Ptilodictya. 
Formation and locality. Hamilton group, near the head of Canandaigua lake, 
Ontario county, N. Y. 
