NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
379 
Measurements. — Aperture j 
,ha= 0.06 mm. 
1 7a~0.08 mm. 
V aviations. — The exterior surface of a zoarium creeping on the roots of algae 
is naturally larger than the surface in immediate contact with the substratum. 
When the calcification is intense and the walls thick, the micrometric difference 
for each zooecium becomes perceptible, as we have established in this species. The 
number of lateral areolae is about six; they are frequently above the aperture; 
their place is inconstant, in no wise regular. The orbicular zoarium contains at 
the center some zooecia somewhat different; they are erect and ornamented with 
a large auriculated vibraculum; they arise from the exaggerated development of 
one of the areolae (fig. 11). The perforations of the lower face of the zoarium 
serve probably as a passage for radical fibers ; they are often surrounded by hollow, 
hydrostatic tuberosities (fig. 13). The tangential section (fig. 10) shows that the 
olocystal elements of the frontal wall are grouped in lines radiating from the 
aperture toward the areolae ; perhaps a very compact pleurocyst covers the olocyst. 
Hippomenella radicata and Schizoporella gemznopora Reuss, 1847, have also 
some radicular pores on their lower face, but they belong to different genera easy 
to differentiate. 
This species differs from Hippoporella multilamellosa in its unilamellar and 
orbicular zoarium, in the absence of a separating salient thread, in the constant 
presence of the pores, and in its transverse aperture. 
Occurrence. — Vicksburgian (Glendon member of Marianna limestone) : West 
bank of Conecuh River, Escambia County, Alabama (common). 
The operculum is contracted laterally. The ovicell is hyperstomial and 
always closed by the operculum. The frontal is bordered with areolar pores. 
Genotype. — Hippoponella ( Lepralia ) hippopus Smitt, 1867. Recent. 
1917. Hippomenella Cantj and Basseer, Synopsis of American Eary Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 41. 
The aperture bears two small cardelles placed very low and separating a large 
porta from a small vanna; it is always semielliptical (in the interior). The 
ovicell, hyperstomial, is deeply imbedded in the distal zooecia ; it opens by a large 
opening above the aperture, but it is never closed by the operculum. The frontal 
is formed of an olocyst perforated laterally by some areolae and supporting a 
pdeurocyst more or less developed. The ovicell bears laterally two areas in the 
form of a lunar crescent and more or less perforated. There are nearly always 
some spines and some avicularia. 
Genotype.- — Hippomenella (Lepralia) mucronelliformis Waters, 1899. 
Range.- — Lutetian-Recent. 
Cotypes. — Cat. No. 64272, U.S.N.M. 
HIPPOPONELLA, new genus. 
Genus HIPPOMENELLA Canu and Bassler, 1917. 
