56 
PALAEONTOLOGY OF NEW YORK. 
The elevated carinse with the connecting bars are very fragile and are want¬ 
ing on the greater portion of the specimens observed. 
Formation and locality. In the shaly limestone of the Lower Helderberg group, 
Clarksville, N. Y. 
Fenestella (Unitrypa) Nervia, var. constricta. 
PLATE XXII, FIGS. 11, T2. 
Fenestella ( ffemitrypa ) Nervia, var. constricta, Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist., p. 
174. 1879. 
“ “ “ “ “ Report of State Geologist for 18S2. Expl. pi. 22, tigs. 
11, 12. 1883. 
Bryozoum infundibuliform, compact. Branches moderately strong, slightly 
diverging, essentially parallel, very gradually increasing in size to the bifur¬ 
cations, marked on the non-poriferous side by from three to six strongly 
granulose striae. Transverse section of branch broadly oval. Bifurcations 
infrequent. Interstices narrow. Dissepiments rounded, granulose, very 
slightly depressed, about eight in the space of 5 mm. Fenestrules oval, width 
from one-half to three-fourths the length. 
On the celluliferous face the branches are angular and the dissepiments 
much depressed. Cell apertures small, sub-circular, in two ranges, opening 
somewhat laterally, twenty-five in the space of 5 mm., distant less than the 
diameter of an aperture: margins strongly elevated on the anterior, indent¬ 
ing the borders of the fenestrules. Branch bearing a very thin carina, which 
is slightly expanded along the summit and connected by irregular lateral 
processes, which sometimes continue from the summit of one carina to that 
of another; at other times they meet midway, coalesce and form an indis¬ 
tinct, irregular ridge. 
Width of branch above a bifurcation .40 mm., increasing to .60 mm. Dis¬ 
sepiments from .20 to .25 mm. in diameter; fenestrules about .40 mm. long; 
height of carina .40 mm., summit .14 mm. wide. 
This variety is easily distinguished by its compact form, sub-parallel branches, 
the usually irregular character of the connecting processes, and the narrow 
summits of the carinae. 
Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 
