NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
151 
CALLOPORA CRASSOSPINA, new species. 
Plate 29, fig. 9. 
Description. — The zoarium incrusts rocks. The zooecia are elongated, distinct, 
regularly elliptical, provided with a small gymnocyst; the mural rim is convex, 
very salient, ornamented with a line of large spines. The opesium is elliptical, en- 
tire. The hyperstomial ovicell, never closed by the opercular valve, is globular, 
projecting, and ornamented with a longitudinal carina. The avicularium is large, 
placed transversally to the zooecial axis, very pointed, and has two denticles serv- 
ing as a pivot. 
M easurements. — Opesia 
ho— 0.32 mm. 
lo= 0.22 mm. 
Zooecia 
[Zs=0.40 mm. 
(fe=0.30 mm. 
Affinities. — The avicularia are so scattered over the zoarium that most of the 
zooecia are not provided with them. At first view this species strangely resembles 
Mernbranipora incrustans Waters, 1898. It differs from it, however, in its larger 
avicularium, its larger spines, and in its ovicell which is hyperstomial and not 
endozooecial. This is only another example in favor of the very great prudence 
which it is necessary to employ in the determination of the Membranipores. 
Callopora crassospina differs from the recent Callopora craticula Hincks, 1877, 
in its transverse avicularia and its greater zooecial length. 
Occurrence. — Middle Jacksonian (Castle Hayne limestone) : Wilmington, North 
Carolina (rare). 
Holotype. — Cat. No. 63926, U.S.N.M. 
CALLOPORA CONVEXA, new species. 
Plate 29, fig. 8. 
Description. — The zoarium is unilamellar and creeps on algae. The zooecia 
are distinct, separated by an oval furrow, narrowed in their proximal portion; 
the lower part is a more or less developed gymnocyst, smooth and convex; the 
mural rim is very thin with a sharp summit. The opesium is elongated, ellip- 
tical, or somewhat oval. The ovicell is hyperstomial, small, globular. Sometimes 
there is an elongated avicularium with pointed beak. 
M easurements. — Opesia 
ho— 0.30—0.34 mm. 
lo= 0.25 mm. 
Zooecia 
\Ls= 0.50-0.75 mm. 
lfe=0.35-0.40 mm. 
Affinities. — Only a few specimens of this species have been found ; nevertheless, 
they have appeared very interesting to us. We are not quite certain that the oper- 
cular valve never closes the ovicell. We are not able to classify the species in 
Membraniporidra in which the zooecial form is often analogous, because of the 
presence of avicularia. 
The convex form of the zooecia and of the gymnocyst characterizes this species 
quite well. 
Occurrence . — Middle Jacksonian (Castle Hayne limestone) : Wilmington, 
North Carolina (rare). 
Holotype . — Cat. No. 63925, U.S.N.M. 
