174 
PALEONTOLOGY OF NEW YORK. 
Fenestella (Ptiloporina) sinistralis, n. sp. 
PLATE XL1II, FIG. 9. 
Bryozoum infundibuliform, length of the largest fragment observed 65 mm. 
with a width of 75 mm. The primary branches, commencing at the base, 
do not increase in size, but have a uniform width of about .60 mm.; the 
secondary branches have a width of about .30 mm., some of these, on the frag¬ 
ments observed, continuing their entire length without increase in size, while 
others attain a width of .60 mm. and have smaller lateral branches; all these 
are straight, angular and slightly carinated; the primary branches are 
strongly elevated above the others. Interstices a little wider than the 
secondary branches. Dissepiments slender, width about .35 mm., angular, 
slightly carinated, on a plane with the secondary branches, six in the space 
of 5 mm. Fenestrules oval, length a little less than .60 mm., width .35 to 
.40 mm. 
On the celluliferous face the dissepiments are rounded and depressed. 
Fenestrules slightly narrower than on the opposite face. Cell apertures in 
from two to five ranges, two ranges occur only immediately above a bifur¬ 
cation, opening outward and laterally, eighteen in the space of 5 mm., 
separated by less than the diameter of an aperture: margins elevated, in¬ 
denting the borders of the fenestrules. 
This species may be distinguished from F. ( Ptiloporina) disparilis by its second¬ 
ary branches, dissepiments and fenestrules, and the more compact appearance of 
the frond ; from F. ( Ptiloporella ) laticrescens by its secondary branches, closer dis¬ 
position of the dissepiments, and by the greater number of ranges of cell aper¬ 
tures, that species having only two ranges; from F. ( Ptiloporella) inequalis it is 
distinguished by its larger branches, dissepiments and fenestrules, the greater 
number of ranges of cell apertures, that species having only two ranges, and 
by the coarser appearance of the frond. From all other similar species, at 
present known, in the fact that the secondary branches proceed only from the 
left side of the primary branches. 
Formation and locality. Upper Helderberg group, Schoharie grit, Schoharie, 
N. Y. 
