Page 187

                     The Coralis of J)elafield.               187
The genus is thus described by Dr. Hall: " A foliaceous branch-
ing coral, supported by smooth rootlike expansions; branches
bifurcating and sometimes coalescing, celluliterous on both sides,
with thin central axis.  Cellules, oval tubes, not enlarged below
apertures, distinctly oval with raised borders, nearly as wide as
the cells within.
  The distinctive features of these species lie in the mode of
branching, size, shape and arrangements of the cells. Their re-
semblance to modern Bryozoan forms is manifest. This resem-
blance is still more plainly seen in the reticulated forms represented
by Fige. 3 and 4.' These are incrusting forms with the cells on
I These figures refer to drawings placed before the association at the pres-
entation of this paper in December, 1878. Some of the corals will be illus-
trated in Vol. IV, Wis. Geol. Surv.
one side only. Fig. 3 is an undescribed species, referred to the
genus Jietopora by Professor Whitfield.  Fig. 4 was described
by Professor Whitfield, and his description is found in the annual
report of the Wisconsin Geological Survey for 1877, p. 68, under
the name Ienestela y)uanulosa.
  The more obvious characters of each form are as follows: The
Retopora presents anastomosing branches with irregular, elliptical
or linear, pointed meshes, upper surface of branches thickly covered
with circular pores which are arranged in three or four longitudinal
rows. In the Fenestella the branches do not reunite after separa-
tion, but frequently bifurcate and are connected at quite regular
intervals by extremely narrow bars which divide the interspaces
into ob'ong spaces or fenestrules.  The pores in this form are ar-
ranged in lines, a single row on each margin of the branches or
rays. The opposite surface of the frond is densely covered with
very minute granules, hence the term granalosa, applied to the
species.
  Turning to those forms which more closely resemble living
radiate corals, we notice first of all the delicately formed
Trernatopora ann?,lifer, Whitfield, described in the Annual Re-
port Wisconsin Geological Survey for 1877, page 67.    Scores
of fragments of this beautiful fossil are found imbedded in