Page 188

188     Wlfisconsin Academy of Sciences, Arts, and Letters.
the surface of some of the blocks of shale, and though their di-
ameter is hardly larger than that of a knitting needle, their pecu1.
iar sharp annulations distinguish them at a glance.  The surface
pores are fine as needle points, yet under the microscope show inl
general an elliptical section and are separated by grooved walls
givingto each opening a distinct margin or rim which is elevated
into a sharp spine on the lower side. The genus Fistalapora ex.
hibits a still further remove from the Bryozoan type.  The larger
cells in this series have plainly marked transverse partitions as in
the Favosite corals.  Still we have in some forms thin incrusting
layers and masses built up by the superposition of these layers.
Our collections contain several new species of this genus, two of
which have been de-cribed. The two forms to which I wish to,
call your attention now are Fi so7i(lissi/ma and F. lens. The sur-
face markings in these species are nearly alike; the former pre-
sents solid, cylindrical or flattened stems, often branching, while
the latter presents disk-like expansions with openings on one side
only. The surface of the former shows very small elliptical cells,
separated by comparatively thick walls or interspaces which are
studded by minute pores arranged in one, two, or sometimes three
rows between the cells. Twelve to sixteen of these larger cells
are found in the space of an eighth of an inch, measured alon1''
the branches. In F. lens the cells are rather larger and the'
interspaces narrower; otherwise the appearance of the surface in
these species is similar.
  The forms already noticed are generally considered to be Bryq.
zoans. The difference of opinion that has been referred to applies
Principally to the remaining forms, and at this point, therefore, we
should look for some important fundamental distinctions.
   The genus StellZpora stands nearest to those just noted, an
therefore, claims our attention. The beautiful form, S. pol
stomella, is one of our most common fossils: and although we 0
tain only fragments of its broad frond like expansions, th
star-like tubercles that stud its surface, when perfectly preserve
render it one of the most attractive species to the casual observe
Our species is identified with the form described by Nicholson
the Ohio reports, but presents some points of difference. T
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