NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
41 
CALLOPORA PARVIROSTRIS, new species. 
Plate 12, fig. 3. 
Description. —The zoarium incrusts the shell of a Pecten. The zooecia are dis¬ 
tinct, separated by a deep furrow, somewhat elongated, ovoid but with irregular 
contours; the mural rim is salient, thin, granular, somewhat enlarged at the base. 
The opesium is of the same form as the zooecium. The ovicell is small, very globu¬ 
lar, smooth, opening below the operculum by a very small orifice. The interzooecial 
avicularium is triangular, suberect, very small with two large condyles for pivots. 
Measurements. —Opesia 
ho = 0.45 mm. 
lo = 0.30-0.35 mm. 
Zooecia 
1,2 = 0.55-0.60 mm. 
lz = 0.45-0.50 mm. 
Affinities. —This species belongs to the C. tenuirostris group in the presence of 
its interzooecial avicularium. It differs from the genotype in its much larger 
micrometric dimensions and in its very small avicularium. 
Occurrence. —Miocene (Calvert formation): 1 mile south of Parkers Creek, 
Calvert County, Maryland (very rare). 
Holotype. —Cat. No. 68451, U.S.N.M. 
CALLOPORA LANCEOLATA, new species. 
Plate 12 fig. 11. 
Description. —The zoarium incrusts oysters. The zooecia are distinct, elon¬ 
gated, fusiform, adjacent to each other by their mural rim; the mural rim is very 
thin, rounded; a little enlarged at the base; the opesium is elliptical, regular; 
traces of three pairs of spines are visible. The ovicell is large, salient, rectangular, 
garnished in front by a large convex area. The avicularium is placed at the base of 
each opesium; it is large, lanceolate; the beak is very salient and directed toward 
the base. 
Measurements .—Opesia 
„ . (2)2 = 0.60-0.70 mm. 
Zooecia 7 . __ 
£2 = 0.35 mm. 
ho = 0.35 mm. 
lo = 0.20-0.25 mm. 
Affinities. —Above the ovicell the avicularium is frequently divided into two 
smaller, symmetrical avicularia. 
This species differs from Amphiblestrum constrictum Ulrich and Bassler, 1904, 
in its much larger avicularia, more elongated zooecia, and in the absence of two 
prominent condyles for the articulation of the operculum. 
Occurrence. —Upper Miocene (Yorktown formation): 3 miles southwest of 
Petersburg (rare) and Beulahland, Bang and Queen County, Virginia (rare). 
Holotype. —Cat. No. 68452, U.S.N.M. 
CALLOPORA CRASSOSPINA, new species. 
Plate 33, fig. 13. 
Description. —The zoarium incrusts bryozoa. The zooecia are distinct, separ¬ 
ated by a furrow, elongated, oval; the mural rim is thin, round, little salient and 
bears distally six large, hollow spines; the opesium is large, oval, entire. The 
avicularium is interzooecial, long, fusiform, with pointed and salient beak. The 
ovicell is globular, salient, smooth. 
12184—23—Bull. 125- 1 
