66 
BULLETIN OF THE LABORATORIES 
eter apart, surrounded by a thin peristome, five to eight, usually six 
or seven, opposite each fenestrule. Longitudinal space between aper- 
tures often faintly striated. Dissepiments very slender, depressed, 
sub-angular. Fenestrules wider than the branches (occasionally two 
or three times), the length equal to two or three times the width; six 
in lo mm. 
On the reverse the branches are strongly rounded and, as usual, 
striated longitudinally. 
Formation and locality: — The typical form of this species is not 
very abundant at Richfield, O., where it is associated with the much 
more common variety next noticed. 
FENESTELLA ALBIDA var. RICHFIELDENSIS, n. var. 
(Plate XIII, Fig. 3-3C.) 
This variety or species differs from the typical form of F. albida 
mainly in the peculiarly irregular and lax growth of its fronds. They 
are also always smaller and not unfrequently much folded while in 
many the expansion is of palmate shape. The largest example seen 
(nearly complete) is 60 mm. long and nearly the same in width. The 
branches are also less straight and the fenestrules more variable in 
size and shape. In some of the specimens a few branches are stronger 
than the rest, and the whole may assume an irregular pinnate arrange- 
ment. Figure 3 represents a portion of such a specimen. On the re- 
verse, also, the branches are usually narrowly rounded or sub-angular, 
a feature not noticed on typical examples of the species. 
This variety brings the species into close proximity with F. filistrt- 
Ulrich a Burlington limestome species. That species, however, is 
less delicate, has the median keel or carina blunt, and the whole sur- 
face finely striated. 
Formation and locality: — Very abundant at Richfield O., asso- 
ciated with numerous species of crinoidea. 
FENESTELLA APERTA, Hall. 
Fenestella apeiia, Hall, 1887. Sixth Ann. Rept, State Geol. p. 58, pi. IV, figs. 1-5. 
Zoarium consis-ting of very delicate expansions. The largest seen 
is over 50 mm. long and less than 20 mm. wide. Another fragment 
is 35 mm, long and 30 mm. wide. 
