132 
PALAEONTOLOGY OF NEW YORK. 
in the opposite direction, twenty-four in the space of 5 mm. (See fig. 4.) 
Interstices oval or lenticular, as wide or wider than the summits of the scalae. 
The summit of the carina extends above the scalae and is very conspicuous, 
sometimes slightly carinated, occasionally with very prominent, sharp nodes. 
This species may be distinguished by the very slender, closely disposed, 
scalae, and by the prominence of the summit of the carina. The non-cellulifer- 
ous face so nearly resembles that of F. variapora that it is not possible to make 
a satisfactory distinction; the celluliferous faces have little resemblance to 
each other. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Fenestella (Unitrypa) acaulis var. inclinis, n. var. 
NOT FIGURED. 
The dissepiments are very oblique, their summits sharp, more or less curved 
and frequently extending upon the branches, which are angular and slightly 
carinated. The non-celluliferous face is very dissimilar to the ordinary forms 
of F. ( V.) acaulis, but the celluliferous face is similar. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Fenestella (Unitrypa) projecta, n. sp. 
NOT FIGURED. 
This species is very similar to F. ( U .) acaulis, but the branches are somewhat 
stronger and more rigid; the dissepiments are oblique and have on the upper 
portion a prominent, paliform node, which projects over the fenestrule. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Fenestella (Unitrypa) transversa, n. sp. 
NOT FIGURED. 
Branches very slender, width above a bifurcation .20 mm., increasing to .30 
mm., sinuous or ziz-zag, angular. Interstices wider than the branches. Dis¬ 
sepiments comparatively strong, width .25 mm., angular, six in the space of 
