148 
PALAEONTOLOGY OF NEW YORK. 
Fenestella (Hemitrypa) favosa. 
HOT FIGURED. 
Fenestella (Hemitrypa) favosa, Hall. Trans. Albany Institute, vol. x, abstract, p. 35. 1881. 
Bryozoum infundibuliform, compact. Branches very slender, bifurcating at 
varying distances; width above a bifurcation .25 mm., increasing to .50 mm.; 
rapidly enlarging when the bifurcations are frequent; often increasing in 
size, then contracting and again enlarging before bifurcation ; angular and 
slightly carinated when well preserved. Interstices of the same width, or 
slightly narrower than the branches. Dissepiments extremely slender, width 
from .15 to .18 mm., angular, slightly carinated, depressed, rounded when 
worn or macerated, from eight to ten in the space of 5 mm. Fenestrules 
oval, length from .35 to .40 mm., width usually about .25 mm. 
On the celluliferous face the frond has a more compact appearance. Dis¬ 
sepiments angular, slightly carinated, much depressed. Fenestrules smaller 
than on the opposite face. Cell apertures in two ranges, opening laterally, 
twenty in the space of 5 mm., separated by a little less than the diameter of 
an aperture; margins equally elevated, slightly indenting the borders of the 
fenestrules. Carina thin, height .25 mm., summit not expanded. Sc aim and 
pseudo-carina of the same strength as the summits of the carinae proper; 
eighteen scalae in the space of 5 mm. The carinae and pseudo-carinae are 
frequently zig-zag, the interstices then having the appearance of hexagonal 
cell apertures; when the carina is broken away the base has the appearance 
of a row of prominent triangular nodes, along the middle of the branch. 
The non-celluliferous face of this species resembles that of F. ( Unitrypo) nana, 
but the branches are more closely disposed, the fenestrules narrower, and when 
the bifurcations are frequent the branches increase in size more rapidly; the frond 
also presents a more compact appearance ; on the celluliferous face the difference 
is at once observed. From F. (U.) columellata it differs by the less uniform size 
of the branches and the more slender dissepiments, those of that species being 
as wide or wider than the branches; on the celluliferous face the summit of the 
carinae and the scalae are more slender. The non-celluliferous face so closely re- 
