Bulletin - United States National Museum - Smithsonian Institution

EARLY TEETIARY CHEILOSTOME BKYOZOA. 51
peristomice (secondary orifice of Hincks) ;
it is irregular and its out-
lines are vague and undefined. The apertura is the zooecial orifice
closed by the operculum; it is not always visible externally. The
internal tube formed by the development of the peristome is the
peristomie.
The calcification functions as in other genera. Nevertheless the
pleurocyst is a frequent occurrence, and the greater part of the time
the two calcareous layers are separable.
Genus SMITTINA Norman, 1903.
1880. Smittia Hincks, British ^Marine Polyzoa, p. 340 (preoccupied).
1903. Smittina Norman, Notes on tlie Natural History of East Finmarli,
Annals and Magazine Natural History (7), vol. 12, p. 120.
In the apertura there is a lyrule and two cardelles. The frontal
is an olocyst, perforated laterally with areolae and supporting a
granular or costulate pleurocyst. The anterior indentation of the
peristome contains an avicularium very often triangular.
Genotype.— Smlttina {Leprdlia) reticulata MacGillivray.
Range.—Lutecian-Eecent.
This genus is represented in the American Early Tertiary by
14 new species and by Smittina tubulata Gabb and Horn, 1862,
from the Vicksburgian, /S'. stromhecJd Eeuss, 1806, from the Middle
and Upper Jacksonian, and S. angulata Eeuss, 1866, from the Jack-
sonian and Vicksburgian.
PLAGIOSMITTIA, new genus.
{Plagios^ transverse, referring to the zocccial arrangement.)
The ovicell opens into the peristomie. The frontal is a tremocyst.
The avicularium is placed in the peristomie. The zooecia are oriented
transversally to the zoarial fronds.
Genotyj)e.— Plagiosmittia regularis., new species. Jacksonian.
This genus differs little from Porella Gray, 1848, in the nature of
its functions. The difference lies in the irregularity of the place of
the median avicularium and in the disposition of the zooecia on the
fronds. Possibly it should be considered only a subgenus.
PLAGIOSMITTIA REGULARIS, new species.
Plate 5, fig. 4.
Description.—The zoarium is bilamellar; the fronds are flat, narrow
bifurcated. The zocecia are much elongated, distinct, separated
by a thread or a furrow, and are much narrowed proximally. The
frontal is flat or little convex, and formed of a tremocyst with numerous
crov.ded pores. The peristome is thin, salient; the aperture