54 
PALAEONTOLOGY OF NEW YORK. 
This species is characterized by its quadrangular fenestrules and its very 
slender dissepiments which do not expand at their junction with the branches. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
UNITRYPA, Hall. 1885. 
Fenestella (Unitrypa) precursor. 
PLATE XXI, FIGS. 1I-1S. 
Fenestella prcEcursor, Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 94. 1874. 
“ “ “ Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 171. 1S79. 
“ “ “ Report of State Geologist for 1882. Expl. pi. 21, figs. 14-15. 1883. 
Bryozoum infundibuliform, not rapidly expanding, growing directly from the 
spreading base without a pedicel. Branches moderately strong, gently 
rounded, very gradually increasing in size to the bifurcations, often sub-paral¬ 
lel for some distance ; marked by two or three coarse granulose strife on each 
branch. The granules or nodes are sometimes so prominent as to obliterate 
all other surface markings, but are often regularly arranged. Interstices 
narrower than the branches. Dissepiments strong, rounded, granulose, six 
or seven in the space of 5 mm., on a plane with the branches. Fenestrules 
oval or sub-quadrangular, width from one-lialf to two-thirds the length. 
\ 
On the celluliferous face the branches and dissepiments are angular and 
the latter much depressed. The fenestrules appear somewhat smaller and 
more regularly oval than on the opposite face. Cell apertures oval, in two 
ranges, opening directly outward and obliquely to the axis of the branch; 
eighteen in the space of 5 mm., separated by less than the diameter of an 
aperture: margins elevated, indenting the borders of the fenestrules. 
Branches carinated; carina thin below, rapidly expanding above, into an 
angular summit with a thin sharp crest along the middle and on each mar¬ 
gin a row of nodes, sometimes appearing like minute apertures. Either on 
account of the more perfect condition of the frond or the more advanced 
stage of growth, the nodes of contiguous carinse are sometimes extended 
until they unite, forming slender bars connecting them. 
Brandies varying in width from .30 to .35 mm., increasing to .75 mm. ; 
diameter of dissepiments .25 mm.; fenestrules from .50 to .60 mm. in length 
