NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
321 
nr , i, • , \hpe=0. 10-0.15 mm, 
M easurements . — Peristomice / „ . „ 
Zooecia 
f Lz= 0.85 mm. 
{fe=0.40mm. 
Affinities . — There is frequently a very small peristoniial avicularium (fig. 10). 
On longitudinal sections the ascopore manifestly opens below the apertura (fig. 
12) ; it often appears like a large funnel (fig. 12). On the ovicelled zooecia there 
is a sort of clamp (pi) which is perhaps intended to fasten the operculum during 
the expulsion of the larva (fig. 11) ; but it is difficult to comprehend the exact posi- 
tion of this operculum and perhaps we have located it badly if the ovicell is 
peristomial. 
This species differs from Gastropella asperula in the more elevated position 
of the ascopore, in the absence of the numerous avicularia on the peristome, and 
in the very large areolae. 
Occurrence. — Midwayan: Mabelvale, near Little Rock, Arkansas (common); 
one mile west of Fort Gaines, Georgia (common) ; Luverne, Crenshaw County, 
Alabama (rare). 
Cotypes. — Cat. No. 62589, U.S.N.M. 
GASTROPELLA ASPERULA, new species. 
Plate 43, figs. 15-18. 
Description . — The zoarium is free and cylindrical. The zooecia are large, 
elongated, little distinct; the frontal is smooth, convex, surrounded by small areolae. 
The ascopore is large, not salient, placed at the middle of the frontal. The peri- 
stome is very salient and bears 2 to 6 small avicularia; the peristomice is elliptical, 
transverse, oblique toward the bottom of the zoarium ; the apertura is semielliptical 
with a concave proximal border. 
M easurements . — Peristomice 
[ ^<3=0.12-0.14 mm. 
lpe—0.20 mm. 
Zooecia 
Lz =0.70-0.72 mm. 
lz= 0.35-0.40 mm. 
Affinities .— This beautiful species is rather constant in its characters. We 
have never been able to find an ovicell in our sections. 
It differs from Gastropella ventricosa in its smaller areolae, its smaller ascopore, 
and in the presence of many small avicularia on the peristome. 
It differs from Phoceana simulator with which it occurs and much resembles 
exteriorly in the presence of an ascopore. 
• Occurrence . — Middle Jacksonian (Castle Hayne limestone) : Wilmington, 
North Carolina (rare). 
Cotypes. — Cat. No. 64037, U.S.N.M. 
Genus PACHYTHECA Canu, 1913. 
1913. Pachytheca Canu, Contribution a l’etude des Bryozoaires fossiles, 12, Bryozoaires 
jurassiques, Bulletin Societe Geologique France, ser. 4, vol. 13, p. 142. 
The frontal is a thick olocyst. The zoarium is free,, and subcylindrical. The 
ascopore is large and opens exteriorly quite a distance from the peristome. 
55899— 19— Bull. 106 21 
