44 PALAEONTOLOGY OF NEW YORK. 



On the celluliferous fttce the branches are angular and the dissepiments 

 depressed. Cell apertures moderately large, circular, in two ranges opening 

 laterally ; eighteen in the space of 5 mm., with interspaces equal to the 

 diameter of an aperture. There is usually an additional aperture imme- 

 diately below a bifurcation. When the specimen is somewhat worn or mac- 

 erated, the apertures appear larger, more closely arranged, and open more 

 upon the side of the branch. 



Width of branches above bifurcation .25 mm., increasing to .50 mm. ; 

 diameter of dissepiments .20 mm.; length of fenestrules from .75 to .80 mm. 



Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 



Fenestella junceus. 



PLATE XX, FIGS 16-18. 



FifnesiieUa jmuxiu. Hall. Thirty-second Rept. N. Y. State Mas. Nat. Hist., ].. 108. 1879. 



" " Reiwrt of State Geologist for 1882. Expl. pi. 20. tigs. 1(5-18. 1883. 



Bryozoum infundibuliform, gradually expanding. Branches slender, slowly 

 increasing in size ; rounded and marked by from six to seven striae on 

 each branch. Width of the interstices about equal to that of the branches. 

 Dissepiments slender, rounded, striated, very slightly expanding at their 

 junction, and on the same plane with the branches. Fenestrules elongate, 

 8ub-quadrangular. 



On the celluliferous face the branches are angular and the dissepiments 

 much depressed. Fenestrules of the same appearance as on the opposite 

 face. Cell apertures comparatively large, circular, in two ranges, opening 

 laterally ; twenty-five in the space of 5 mm. ; separated by a distance equal 

 to the diameter of an aperture ; margins slightly elevated. 



Width of a branch above bifurcation .30 mm., increasing to from 50 to 

 .60 mm.; diameter of dissepiments .25 mm.; length of fenestrules gener- 

 ally 1 25 mm., sometimes 1.50 mm., width from .25 to .40 mm., usually 

 about .33 mm 



Formation and locality. Lower Helderberg group, Clarksville, N. Y. 



