42 
PALAEONTOLOGY OF NEW YORK . 
and closely disposed, very frequently in contact and always distant less than 
the diameter of an aperture: margins strong, elevated, those of the outer 
ranges projecting beyond the branch. Branches usually round, but some¬ 
times decidedly angular. Diameter of specimens 15 mm. or more. 
The very frequent bifurcations and the clavate branches are distinguishing 
features of this species. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
Thamniscus fruticella. 
PLATE XXII, FIG. 33. 
Thamniscus fruticella, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 176. 1879. 
“ “ “ Report of State Geologist for 1882. Expl. pi. 22, fig. 83. 1883. 
Zoarium consisting of a main stem and lateral branches, Bifurcations frequent, 
occurring, on the specimens observed, at intervals of about 4 mm. Branches 
above the bifurcation 1 mm. wide, increasing to 1.50 mm.; clavate; non- 
celluliferous face rounded, striated. The celluliferous face has not been ob¬ 
served, but some of the branches of the non-celluliferous face have been so 
much worn by maceration, that the bases of the cells can be seen. They are 
numerous, three in the space of five mm., and irregularly arranged. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
Thamniscus l Cisseis. 
PLATE XXII, FIGS. 24-30. 
Thamniscus? Cisseis, Hall. Thirty-second Rept. N. Y. State Mus. Nat Hist, p. 170. 1879. 
In part Thamniscus ? Cisseis, Hall. Report of State Geologist for 1882. Expl. pi. 22, figs. 23-30. 1883. 
Zoarium ramose, solid; celluliferous on one face. Bifurcations occurring at 
intervals of from 3 to 4 mm. Transverse section of a branch circular, 
diameter 1 mm. Branches more or less curved; on the non-celluliferous 
face marked by fine, numerous strife. Cells tubular, length about .75 mm., 
regularly curving and gradually enlarging to the surface. Apertures circular 
or broadly oval, sometimes sub-polygonal from mutual pressure; diameter 
about .30 mm.; those nearest the margin are larger and more oval than the 
