64 PALEONTOLOGY OF NEW YORK. 



This species is charivcterized 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) PRiECURSOR. 



PLATE XXI, FIGS. 14-18. 



PmeiMla prOBenrtor, Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 94. 1874. 

 " " " Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 171. 1879. 



" " " Report of State Geologist for 1882. Expl. pi. 21, figs. 14-18. 1883. 



Brtozoum 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 disUuice ; marked by two or three coarse granulose striae 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-half 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 carinae are sometimes extended 

 until they unite, forming slender bars connecting them. 



Branches 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 



