p. 17




Status: Complete


the summit (and rarely, a little contracted below). The dome
plates are slightly nodose, often a little pointed, but in this
respect variable.
This is a well marked species, and the specimens vary in
height from less than half and inch, to an inch and three-
eighths without important differences. When well preserved,
the projecting arm-bases give a somewhat pentalobate aspect
when viewed from the summit.

Geological Formation and Locality. In the drift about Mil-
waukee, supposed to be from rocks of Devonian age. I am
indebted to Mr. I.A. Lapham for specimens from this locality.
I have also received from Rev. W.H. Barris, of Burlington,
Iowa, a specimen of the same species from Iowa City, and
presumed to come from the rocks in that neighborhood, which
are of Devonian age. Specimens collected by Dr. P.R. Hoy,
T.J. Hale and James Hall.


Description. Body below the arms sub-hemispherical, some-
what flattened at the base, with a narrow, deep, pentagonal
basal cavity, formed entirely of the basal plates: which are
long and gradually expanding towards their outer ends. First
radial plates separated from the basal cavity by a deeply chan-
neled suture, their width once and a half their height, and
widest a little above the middle, upper margins concave. Second
radials quadrangualr, much wider than high; third radials
hexagonal, larger than the second, widest near the base.
First supra-radials but little smaller than the third radials.
Socond supr-radials much smaller than the first, pentagonal,
supporting on each upper sloping side a small brachial
plate upon which rest the arm plate. The first interradial
plate is the largest plate in the body, irregularly ten sided,
height and width equal; supporting the second plates side by
side on its upper edge. Intersupra-radial plates one in each
series, proportionally small. Arms and interbrachial plates
Surface marked by moderately strong, irregularly radiating,
interrupted lines with deep pits; sutures of plates rather widely
This species differs from E. coelatus (Pal. N.Y., vol. 2, pl.
47, fig. 4,) in the more nearly hemispherical cup, while the
surface ornaments are lines more properly than granules, and

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