NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
141 
Measurements.- 
. , |k = 0.08 mm. 
-Apertura^ _ al0 
mm. 
Zooecia 
\Lz = 0.40 mm. 
\lz =0.20-0.30 mm. 
Affinities. —This species is very easy to recognize by its interareolar radiating 
costules; however, this character is much less apparent on the zooecial margins 
where the pleurocystal calcification is incomplete. 
Occurrence. —-Pliocene (Caloosahatchee marl): Shell Creek, De Soto County, 
Florida (very rare). 
Holotype. —Cat. No. 68634, U.S.N.M. 
Family EURYSTOMELLIDAE Levinsen, 1909. 
Levinsen’s original description is as follows: 
No spines. The thick-walled and strongly calcified zooecia lack a covering membrane and have 
either no pores at all or 2-5 extremely large fenestrae. The broad aperture, which has a concave proxi¬ 
mal rim, is provided with a more or less strongly chitinized operculum surrounded by a continuous 
marginal thickening. No avicularia. The ooecium is enclosed in a kenozooecium, the frontal wall of 
which is provided with a very large uncalcified part. Pore-chambers [dietellae] or groups of uniporous 
rosette-plates [septulae]. 
The two known species classed in this family are Lepralia foraminigera Hincks, 
1883, and Lepralia bilabiata Hincks, 1884. Levinsen believed that the second 
species is probably the type of a special genus while the first is the type of the genus 
Eurystomella. 
Fig. 26.—Genus Eurystomella Levinsen, 1909. 
A-C. Eurystomella bilabiata Hincks, 1884. A. Sketch showing the operculum dissected out; rb, 
outer rib; rb', inner rib; in. op., inner operculum; or, orifice; lat. mem., lateral membrane; fd. mem., 
folded membrane; ac, accessory lip; ou. op., outer operculum. B. A few adult zooecia, X 30; th. r, 
thickened rim; op, operculum; um, umbo; k, keel. C. A few zooecia at the growing edge of the colony 
showing the membranous aperture of the imjnature zooecia (im. zoe.) (A-C, after Robertson, 1908.) 
D-F. Eurystomella foraminigera Hincks, 1883. D. Two gonozooecia and an ordinary zooecium, 
X 40. E. Three zooecia, from the basal surface, which has a large uncalcified central part, X 40. F. A 
sagittal section through a zooecium with ovicell, X 40. The orifice of the ovicell is closed by the 
ectocyst. (D-F, after Levinsen, 1909.) 
