14 
PALAEONTOLOGY OF NEW YORK. 
ClLETETES (MONOTRYPELLA) DENSUS. 
PLATE X, FIGS. 11-13. 
Trematopora densa, Hall. Twenty -sixth Rept. N. Y. State Mus. Nat. Hist., p. 105. 1S74. 
Trematopora ( Chastetes ) densa. Hall. Thirty-second Rept N. Y. State Mus. Nat. Hist., p. 150. 1879. 
" “ “ “ Report of State Geologist for 1882. Expl. pi. 10, figs. 11-13. 1883. 
Corallum ramose, solid; diameter of branches from 3 to 4 mm. Cells tubular, 
polygonal, arising from the center of the branch and quite regularly curving 
to the surface; diameter at the apertures somewhat variable, but generally 
about .33 mm.; walls thin, sometimes becoming much thickened at the sur¬ 
face, constricting the apertures ; frequently spinulose at the angles. Septa 
thin, occurring only near the surface. Surface marked by occasional 
maculse, where the cells are larger than on other portions, having a 
diameter of .50 mm. 
Formation and localities. In the shaly limestone of the Lower Helderberg 
group, at Catskill creek, and near Clarksville, N. Y. 
PT YCHONEM A, n. g. 
Ptychonema, 11 . s. g. 
Distinguished by the strong corrugations of the cell walls and absence of septa. 
Ciletetes (Ptychonema) tabulatus. 
PLATE IX, FIGS. 12-15. 
ChcBtetes tabulatus, Hall. Illustrations of Devonian Fossils, Corals : PI. 37, figs. 16-19. 1876. 
“ “ “ Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 149. 1879. 
“ ? “ “ Report of State Geologist for 1882. Expl. pi. 9, figs. 12-15. 1883. 
Corallum forming spheroidal or hemispheric masses. Diameter of the largest 
specimen observed 45 mm. Cell tubes polygonal, arising from the center of 
the base and increasing by interstitial additions. Diameter at the aperture 
about .50 mm.; walls thin, very strongly and regularly corrugated, the cor¬ 
rugations forming nodes at the angles ; about fifteen corrugations in the space 
of 5 mm. Septa, so far as observed, wanting. 
Formation and locality. Probably from the Upper Helderberg group, Scho¬ 
harie, N. Y. 
