194 
PALEONTOLOGY OF NEW YORK. 
very infrequent. Cell apertures oval, length .25 mm., width two-thirds the 
length, disposed in longitudinal, sometimes twisted rows, often alternating and 
forming oblique transverse rows. The apertures near the basal portion of 
the frond are distant from each other about the width of an aperture, above 
this they are more closely disposed; the inter-apertural surface is flat, striated, 
striae granulose. On some portions of the frond the apertures are nearly 
in contact, the surface between them slightly elevated, angular and gran¬ 
ulose, inclosing the apertures in polygonal areas. 
This species may be distinguished from Nemataxis simplex by its larger cell 
apertures, their less distinct arrangement in longitudinal rows, and the more 
prominent granulae : from Trcmatopora ( Orthopora) orbipora by the more oval 
apertures, more distinct arrangement in longitudinal rows and the granulose 
striations. 
Formation and locality. Hamilton group, Darien Centre, Erie county, N. Y. 
Bactropoha curvata, n. sp. 
PLATE LXVI, FIGS. 14-16. 
The specimens observed consist of simple stipes, but it is probable that larger 
specimens would show a ramose character: diameter .75 mm., base obtusely 
pointed. Cell apertures oval, length .25 mm., width one-half the length, 
disposed in longitudinal parallel rows, distant the width of an aperture. Six 
or seven rows on a branch, separated by comparatively prominent nodose or 
granulose ridges; nodes small, one or two ranges on each ridge, the other 
portions of the surface similarly ornamented. 
This species is peculiar and will be readily distinguished from any species at 
present known in this geological formation. 
Formation and locality. Hamilton group, Canandaigua lake, N. Y. 
