NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
87 
CONOPEUM ORNATUM, new species. 
Plate 3, fig. 2. 
Description -. — Zoarium bilaminate. The zooecia are distinct but separated by 
a common elevation. The mural rim is somewhat rounded and almost everywhere 
of equal breadth. The opesium is median and elliptical. The interopesial cavities 
are distinct and irregular. 
Affinities . — The ornamentation of its surface renders this species absolutely 
characteristic, although this feature is reproduced sometimes in other species, but 
only accidentally. Unfortunately we possess but a single fragment of this inter- 
esting form. 
Occurrence. — Midw.ayan (Clayton limestone) : Mabelvale, near Little Rock, 
Arkansas (very rare). 
Holotype. — Cat. No. 63788, U.S.N.M. 
CONOPEUM DAMICORNIS, new species. 
Plate 3, figs. 3-8. 
Description . — The zoarium is free, formed of two lamellae growing back to 
back, irregularly bifurcated; the fronds are distorted. The zooecia are distinct, 
irregular, polygonal, or elliptical; the mural rim is very thin, regular, projecting 
but little, convex. The opesium has the same form as the zooeeium. The mter- 
opesial cavities are polygonal and of a very great. irregularity. 
Measurements . — Opesia 
jAo=0.32 mm. 
I lo= 0.20 mm. 
Zooecia 
\Lz= 0.35 mm. 
\lz= 0.23 mm. 
Variations and affinities . — This species has zooecia of a disconcerting irregu- 
larity ; it is absolutely impossible to discover among them a form the least constant. 
The same holds true with the interopesial cavities which disappear following the 
irregularities of the zoarium. 
The structure of the zooecial walls is quite remarkable. In tangential sec- 
tions (fig. 6) these walls appear normal but in transversal thin sections, they are 
thickened, crenulated on the inside, and composed of tissue not very dense (fig. 5). 
In the median thin sections obtained by rubbing away both sides of the fronds, a 
structure may be noted identical with the zooecial walls; the olocystal elements 
grouped around the mural rim appear to be chambered (fig. 7). Finally, a section 
taken perpendicularly to the plane of the fronds (fig. 8) shows that the zoarium is 
formed of two lamellae placed back to back and separable. 
The false chambering of the mural rim is not analogous to the formation of 
dietellae in Periporo sella; we find in reality in every species chambered in this 
way some lai'ge, scattered, unoriented olocystal elements (figs. 4, 6). 
The zoarium itself is quite constant and characteristic; it often assumes, 
although rather vaguely, among other shapes, the form of the Korns of a deer , hence 
our specific name. As its zoarial dimensions exceed two centimeters, we may con- 
