NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
159 
similar to those of M embranipora spiculosa , occur not infrequently upon the Cre- 
taceous specimens but are wanting on the Eocene material in hand. When these 
occur they take the place of the avicularium which otherwise occurs invariably on, 
or just above, the upper rim of the zooecium. (Ulrich, 1901.) 
Occurrence. — Cretaceous (Vincentown) : Mullica Hill and Vincentown, New 
Jersey (common). 
Lowest Eocene (Bryozoan bed at base of Aquia formation) : Upper Marlboro, 
Maryland (rare). 
AMPHIBLESTRUM PRODUCTUM, new species. 
Plate 4, figs. 2, 3. 
Description.— The zoarium incrusts rocks and shells. The zooecia are small, 
very elongated , distinct, often with a small gymnocvst; the mural rim is salient, 
being enlarged below into a concave cryptocyst nearly as long as the opesium. The 
opesium is small, anterior, elliptical, entire. The hyperstomial ovicell, never closed 
by the operculum, is elongated, very salient, and has a frontal carina. The avicu- 
laria are narrow, long, fusiform, pointed, and slightly projecting at the top, 
without pivot. 
~ |Ao=0.15 mm. 
J\l CQ/SVsVClTlCTltS, Op6Sl£l I 7 r\ -a r\ r\ -t r\ 
17(9=0.10-0.12 mm. 
Avicularia Lav— 0.20A).25 mm. 
Zooecia 
[Z^=0.35 mm. 
170=0.20-0.25 mm. 
Variations, affinities. — The length of the avicularia is very variable; they are 
frequently primoserial; their mandible must be triangular. The ovicell has no 
callosity, but is ornamented with a longitudinal keel. This change in ornament 
has no generic importance. 
The zooecia have a little resemblance to Amphiblestrum curvatum , but the 
present species differs from the latter in its straight avicularia. 
Occurrence.- — Midwayan (Clayton limestone) : One mile west of Fort Gaines, 
Georgia (rare); Luverne, Crenshaw County, Alabama (rare). 
Cotypes. — Cat. Nos. 63796, 63797, U.S.N.M. 
AMPHIBLESTRUM BIPOROSUM, new species. 
Plate 29, figs. 13, 14. 
The zoarium incrusts shells. The zooecia are small, wide, pyriform, and dis- 
tinct; the cryptocyst is concave and as long as the opesium. The opesium is ante- 
rior, somewhat trifoliate. The ovicell is hyperstomial and never closed by the 
operculum. Below each zooecium there are two small simple avicularia, slightly 
projecting, round or elliptical, irregularly placed, leaving two pores on the fossils. 
,, , r, 7?o=0.15 mm, 
M easurements. — (Jpesia 7 . . . 
7o=0.10 mm. 
Zooecia 
j Zs=0.30-0.32 mm. 
[7,3=0.25 mm. 
Affinities.— The cryptocyst is formed simply by the progressive enlargement 
of the mural rim. This species has the aspect of Dacryonella octonariuw. but differs 
