NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
287 
MEMBRANJPORELLA ULRICHI, new species. 
Plate 41, figs. 4, 5. 
Description.- — The zoarium is free, bilamellar, bush-like. The zooecia are 
little distinct, joined together by their mural rim, thin, very elongated, lozenge- 
shaped ; the cribriform area is shallow, flat, and contains 10 to 12 very narrow trans- 
verse slits; the axis of the suture of the costules is salient. The aperture is elon- 
gated, semilunar; its proximal border is provided with a quite salient thorn-like 
projection. The ovicell is large, embedded in the distal zooecia, salient, globular, 
always closed by the operculum, and formed of two calcareous lamellae, of which the 
outer one is porous. The two oral avicularia are large, fusiform, and prominent; 
the pivot is indicated by two small, lateral teeth. 
it* , . , \ha= 0.17 mm. „ . fZs=1.00 mm. 
Measurements. — Aperture , Zooecia 7 . .. 
1 \ia— 0.15 mm. I lz= 0.3 5-0.40 mm. 
Affinities. — This fine species is very constant in all its characters. A tangential 
thin section (fig. 5) shows that the costules are formed of rather large, scattered 
olocystal elements, regularly placed. 
MembraniporeTla ulrichi differs from M embranipordla planula in its mural 
rims, which join each other; in its much larger avicularia (Zt'=0.25 mm.) ; in the 
extreme thinness of the lumen (0.01 mm.), and in the sharpness of the proximal 
border of the aperture. 
It can be distinguished from Membranipordla bioculata by its small and non- 
bifurcated oral prominence, by its much smaller and more numerous costules, by its 
larger avicularia (Lv= 0.25 mm.) and by its much longer ovicells (hov 0.20 mm. 
instead of 0.15 mm.). 
We dedicate this species to Dr. Edward O. Ulrich, whose brilliant work on 
the Paleozoic bryozoa has a world-wide reputation, and who was among the first 
to take up the serious study of the American Tertiary forms. 
Occurrence.— Middle Jacksonian: near Lenuds Ferry, South Carolina (abun- 
dant) ; Eutaw Springs, South Carolina (abundant) ; Wilmington, North Carolina 
(rare). 
Cotypes. — Cat. No. 64016, U.S.N.M. 
MEMBRANIPORELLA BIOCULATA, new species. 
Plate 41, figs. 11-13. 
Description. — The zoarium incrusts bryozoa. The zooecia are distinct, sep- 
arated by a furrow, elongate, elliptical; the cribriform area is very convex, con- 
taining five or six pairs of radial slits. The costules have a lumen pore at the loop. 
The aperture is semilunar; the proximal edge has a large bifurcated mucro, the 
branches of which frequently rejoin the oral avicularia, thus forming a new orifice 
above the aperture; distal spines are sometimes present. The ovicell is prominent, 
globular, smooth, little sunken in the distal zooecia, always closed by the operculum. 
The two oral avicularia are salient, oval, the point at the top ; the pivot is cal- 
careous or simply indicated by two lateral denticles. 
