NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
73 
Fig. 12.—Genus Hemiseptella Levinsen, 1919. 
Figs. A-N. Hemiseptella labiata Busk, 1884. 
A. A branch of the form Vincularia elegans (after D’Orbigny, 1839). B. A branch from Cape 
Horn, X 12. A few minute denticles or hooks occur on the border of the opesium. C. Several zooecia 
of the type of Vincularia elegans preserved at the Museum of Paris. A growth from each side forms a 
calcareous bridge over the opesium. It is placed under the membraneous ectocyst. D. A calcined 
zooecium of a specimen from the Atlantic ( Challenger collection), X 25. E. Transverse section, X 25. 
F. Calcareous section diagonally through a zooecium, thus showing the projecting rosette plates (sep- 
tulae), X 25. G. Section through the dietellae, X 250. H. Diagrammatic section showing the position 
of the septulae, X 25. I. Transverse, decalcified section, X 25. J. A branch, natural size (after 
D’Orbigny, 1839). K. Section in the zooecia, X 25. Besides the lip which projects upward, the front 
wall of the zooecium is directed downward thus contracting the zooecium near the aperture. (Figs. 
D-H, K, (after Waters, 1889). L. Transverse section in operculum, X 85 (B, C, I, L, after Waters, 
1895). M., N. Operculum (after Busk 1884). 
Fig. 0. Hemiseptella denticulata Smitt 1872. A zoarium from Florida. The unshaded zooecia 
are covered by the ectocyst. They show the chitinous arch of the opercular valve. 
Fig. P-S.— Hemiseptella steganoporoides MacGilliVray, 1881. P. A zoarium, natural size, from 
Prince Edward Island. Q. Zooecia with their opesiular in dentations and occasionally the bridge, X 25 
(forma Vincularia gothica). R. A zooecium showing the sutures between the three processes and the 
avicularium (after Waters, 1889). S. Operculum, X 85 (figs. P, Q and S, after Busk, 1884). 
Figs. T-V.— Hemiseptella michaelseni Calvet, 1904. T. Zooecia, X 25, showing the three groups of 
spinous processes bordering the opesium. U. A zooecium covered by its membranous transparent 
ectocyst under which the spinous processes are seen. Y. Operculum, X 85 (T-V, after Calvet, 1907). 
This species is much smaller than Hemiseptella rectangulata, in which the form 
of the zooecia is identical but which is deprived of tubercles. 
Occurrence. —Pleistocene: Simmons Bluff, Yonges Island, Charleston County, 
South Carolina (rare). 
Holotype. —Cat. No. 68492, U.S.N.M. 
HEMISEPTELLA FISTULA Ulrich and Bassler, 1904. 
Plate 14, fig. 9. 
1904. Membranipora fistuln Ulrich and Bassler, Bryozoa: Maryland Geological Survey, Miocene, 
p.>413, pi. 112, fig. 5. 
The original description is as follows: 
Zoarium so far as observed forming small, hollow, subcylindrical stems, about 1.5 mm. in diameter, 
composed of twelve to fifteen longitudinal rows of zooecia. Walls about as wide as the 
zooecial openings, obtusely carinate, the carinae between the ends of the cells high and 
bent forward so as to impart a slightly imbricating appearance to successive cells. Opesial 
opening elongate elliptical; immediately behind it a minute pore is occasionally notice¬ 
able. Measuring longitudinally about 8 zooecia in 5.0 mm. No avicularian nor vibracular 
cells observed. 
The original description of this slender rod-like bryozoan gives an adequate 
idea of the species, of which unfortunately no more specimens have been discovered. 
We reproduce a new illustration of the type specimen which shows spines irregularly 
distributed on the proximal border of the opesium, thereby causing the species to 
be referred to Hemiseptella. 
Occurrence .—Miocene (St. Mary’s formation): St. Maly’s River, Maryland 
(very rare). 
Holotype. —Cat. No. 68493, U.S.N.M. 
12184—23—Bull. 125-6 
