NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
277 
Genotype. — -Macropora centralis MacGillivray, 1895. 
Range. — Jacksonian-Becent. 
Levinsen classed this genus in the Microporidae, but the absence of the opesiules 
and parietal muscles oblige us to place it under the Pseudostega. Perhaps it will 
be convenient to create a family of Macroporidae ; but we are absolutely without any 
knowledge of its anatomical features. 
MACROPOBA AQUIAE, new species. 
Plate 1. figs. 20, 21. 
Desolation . — The zoarium incrusts small shells. The zooecia are hexagonal, 
somewhat elongated, distinct, separated by a more or less salient thread; the crvpto- 
cyst is very slightly concave and quite finely porous. The aperture is semilunar, 
transverse; its proximal border 
is straight with two small lateral 
characteristic indentations ; the 
vestibular arch is very small. 
There are two pairs of lateral 
dietellae. 
Measurements.— \ ha= 0.04 mm. 
Aperture I la= 0.08 mm. 
[Lz—OAO mm. 
Zooecia 
fe=0.20 mm. 
V aviations and aifinities . — 
The micrometric measurements 
are quite variable. The ances- 
trula is a zooeciiun identical with 
the others. The thread separat- 
ing the zooecia often becomes 
quite attenuated. The vestibular 
arch is visible only when greatly 
magnified. 
The frontal occasional lv bear; 
D 
C x40 
A *23 
Fig. 78. — Genus Macropora MacGillivray, 1895. 
A-D. Macropora centralis MacGillivray, 1895. A. Three 
zooecia, X 23.; va, vestibular arch. B. The aperture of a 
special form of zooecium (avicularium?), X 40. C. An 
operculum with its surroundings, X 40. D. A dietella, X 
40. (A-I) after Levinsen, 1909.) 
some perforations which appear to be opesiules. 
This small species is extremely fragile. It is not rare in the Aquia forma- 
tion, to which it appears to be restricted. 
Occurrence . — Lowest Eocene (Bryozoan bed at base of Aquia formation): 
Upper Marlboro, Maryland (not uncommon). 
Ilolotype. — Cat. No. 63780. U.S.N.M. 
MACROPORA MULTILAMELLOSA, new species. 
Plate 41. figs. 1-3. 
Description . — The zoarium is multilamellar and incrusts algae or creeps over 
the sand ; the zooecia of the upper and external lamella only are living. The ex- 
ternal zooecia are hexagonal, elongated, distinct, separated by a prominent thread ; 
