234 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
species on account of the thickness of the mural rim and the elliptical form of 
the avicularian opesium. 
Occurrence. — Middle Jacksonian: Near Lenuds Ferry, South Carolina (rare) ; 
Eutaw Springs, South Carolina (rare). 
Cotypes. — Cat. No. 63991, U.S.N.M. 
AECHMELLA FILIMARGO Canu and Bassler, 1917. 
Plate 37, figs. 3-5. 
1917. Aechmella ftlimargo Canu and Bassler, Synopsis of American Early Tertiary 
Cheilostome Bryozoa, Bulletin 96, United States National Museum, p. 29, pi. 3, fig. 5. 
Description. — The zoarium incrusts Orbitoides. The zooecia are elongated, 
distinct, separated by a furrow or united by their mural rims; the mural rim is 
thin , incomplete, convex, distinct from the cryptocyst. The cryptocyst is shallow, 
oblique toward the opesium, flat, finely granulose; the opesium is transverse, con- 
stricted by two lateral teeth at the level of the rotary axis of the operculum; the 
polypidian convexity projects but little; the opesiular indentations are large, round, 
and symmetrical. The ovicell is endozooecial and small. The ancestrula is a 
small zooecium, but otherwise identical with the others. The avicularium is inter- 
zooecial, smaller than the zooecia, lozenge-shaped, with small distal canal and a 
round opesium. 
M easurements . — Opesium 
y 
Marginal zooecia 
| /? = 0.12 mm. 
Uo=G.16 mm. 
j Ls=0.50 mm. 
| lz= 0.30 mm. 
(including the opesiules) 
Affinities. — This species differs from Rhagasostoma Tevigatum in having an 
endozooecial ovicell. It may be distinguished from Aechmella erassimargo by its 
filiform mural rim. 
Very often the proximal border of the opesium is simply undulated and the 
opesixdes are visible only on account of the opesiular teeth. The opesia of the 
ovicelled zooecia seem a little larger than the others. 
Occurrence. — Upper Jacksonian (Ocala limestone) : West bank of Sepulga 
River, Escambia County, Alabama (rare). 
Cotypes. — Cat. No. 62555, U.S.N.M. 
Genus MICROPORA Gray, 1848. 
1848. Micropora Gray, Catalog List British Animals in British Museum, pt. 1, Centroniae, 
p. 115. 
The two opesiules, which are more or less constant, have the form of simple 
perforations. Spines may appear. The ovicells are endozooecial, but very promi- 
nent, and the small avicularia, which are situated proximally in the aperture, are 
furnished with a complete crossbar (after Levinsen ) . Dietellae with few pores. 
Genotype. — Micropora ( Flustra ) coriacea Esper, 1791. 
Range. — Midwayan. — Recent. 
