NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
401 
HIPPOZEUGOSELEA MARGINATA, new species. 
Plate 53, figs. 9-11. 
Description. — The zoarium is free, bilamellar; the two lamellae are separated 
by some zooeciules; they are biserial. The zooecia are little elongated, distinct, 
rhomboidal, separated by a salient thread; the frontal is convex and formed by a 
tremocyst with large polygonal pores. The aperture is elliptical, oblique; the 
peristome is thin, little salient, interrupted toward the back by a small, inconstant 
tongue. The ovicell is hyperstomial, globular, salient, covered with tremopores like 
the frontal. 
Measurements. — Aperture j ^ q'iq- mm ‘ 
1 mm. 
Zooecia 
Zs=0.85-0.95 mm. 
fe=0.45-0.55 mm. 
Affinities. — This new species differs from Tlippoze.ugoscl.la arcuata in the 
zooeciules which separate the lamellae (fig. 11) and in its zooecial length smaller and 
less than 1 mm. 
It differs from 77 ippozeug osella infata- in the absence of peristomial avicularia 
and in the size of its tremopores. 
Occurrence . — Lower Jacksonian (Moodys marl) : Jackson, Mississippi (rare). 
Cotypes . — Cat. No. 64100, U.S.N.M. 
HIPPOZEUGOSELLA INFLATA, new species. 
Plate 53, figs. 12-20. 
Description . — The zoarium is free, bilamellar: each lamella is biserial. The 
zooecia are elongated, distinct; the frontal is very convex and formed of a tremo- 
cyst with very small pores. The aperture is somewhat elliptical or orbicular; 
two very small cardelles separate the anter from the smaller poster; the pei'istome 
is little salient and is interrupted by a small, distal tongue. Two large tubular 
avicularia are placed symmetrically on each side of the aperture. 
M easuremen ts . — A pert u re 
f Aa=0.12-1.14 mm. 
I '/a— 0.10 mm. 
Zooecia 
I ,fis=0.60-0.80 mm, 
Us=0.40 mm. 
Variations. — The young zooecia are provided with a small distal tongue (fig. 
12) and the avicularia there are replaced by some tuberosities. The edge of the 
zoarium sometimes presents some intercalated zooeciules (figs. 17, 19), although 
sometimes they are wanting (fig. 18). Under the influence of calcification the 
zooecia are flat or very convex (fig. 14) or very wide (fig. 16). 
Affinities.— 1 This species differs from HippozeugoseUa marginata and ITippo- 
zeugoseila arcuaia in the spesence of the two avicularia. 
In its general aspect and its avicularia it has much resemblance to Tlippo- 
zeugosella sexordinata ; but it differs in the disposition of its zoarium, which 
possesses only four longitudinal rows of zooecia. 
Occurence.- — Middle Jacksonian: One-half mile southeast of Georgia Kaolin 
Co. Mine, Twiggs County, Georgia ; Baldock, Barnwell County, South Carolina. 
Cotypes. — Cat. Nos. 64101, 64102, U.S.N.M. 
55899— 19— Ball. 106 26 
