146 
PALAEONTOLOGY OF NEW YORK. 
irregularly disposed, at other times in one or more longitudinal lines; there 
are also fine, slightly elevated striations; when worn or macerated the 
branches are flattened and smooth; bifurcations frequent. Interstices nar¬ 
rower than the branches. Dissepiments very slender, width about .18 mm., 
rounded or sub-angular, very slightly depressed; nine in the space of 5 mm. 
Fenestrules oval, length .40 mm., width from .15 to .20 mm. 
On the celluliferous face the dissepiments are very much depressed, rounded. 
Fenestrules very narrow. Cell apertures in two ranges, opening outward, 
twenty in the space of 5 mm., separated by the diameter of an aperture: 
margins elevated, indenting the borders of the fenestrules. Carina having a 
height of about .30 mm., thin, expanded and flat at the summit, width about 
.12 mm., frequently sinuous or zig-zag. Scalm and pseudo-carina flat and of the 
same width as the carinse; twenty scaloe in the space of 5 mm. Interstices 
circular, diameter about .25 mm. Around each fenestrule is a slight elevation, 
which gives to the summit of the carinoe and scaloe the appearance of being 
concave. From each one of the scaloe there is a slight elevation on the 
sides of the carina extending inward to the branch ; in peculiar conditions of 
weathering the intermediate thinner portions of the carina are destroyed, 
leaving the summit with the appearance of being supported by rows of 
minute columns. 
This species may be distinguished by the characteristic pedicel, and by the 
elevation around the interstices of the hemitrypic face; also when ornamented, 
by the peculiar appearance of the nodes of the non-cellnliferous face. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Fenestella (Hemitrypa) columellata. 
NOT FIGURED. 
Bryozoum infundibuliform, frond compact. Branches slender, width above a 
bifurcation .25 mm., increasing to .40 nun., very gradually enlarging, straight 
or sinuous, angular or sub-angular, slightly carinated, usually with a small 
node opposite each dissepiment; bifurcations comparatively distant. Inter¬ 
stices narrower than the branches. Dissepiments, compared with the 
