Bulletin - United States National Museum - Smithsonian Institution

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16 BULLETIN 96, UNITED STATES NATIONAL MUSEUM. Occun^ence.—Middle Jacksonian : Rich Hill, 5^ miles southeast of Knoxville, Crawford County, Georgia (abundant), and many other localities. Tijpe.—Cat. No. 62573, TJ.S.N.M. SECTION II. INTERZCECIAL AVICULARIA DIFFERENTIATED. HINCKSINA MEGAVICULARIA, new species. Plate 1, fig. 7. Description.—The zoarium incrusts other bryozoa. The zooecia are large, distinct, elongated, pyriform, and have a gymnocyst; the mural rim is convex, salient, provided with 14 to 20 large hollow spines. The opesium is terminal, elliptical, or somewhat pyriform, entire; the interzooecial avicularium is large, symmetrical, and has a gymnocyst; its opesium is constricted laterally, probably at the place where the pivot ought to be. ,, • ^ ^ Measurements.—Upesia , „^„ „ . ^ fAo=0.30-0.35mm. /(?= 0.25mm. I fZs=0.60-0.70mm. 2^^^^^{ fe=.0.40mm. Length of avicularia=0.60-0.65mm. Affinities.—On account of its large avicularia this species ap- proaches the recent Hlncksina pyrula Hincks, 1881. It differs, nevertheless, in its larger number of spines; unfortunately we are unable to compare the ovicells. The specimen figured is very instructive. On a zocecium can be seen the coalescing of opposite spines giving an aspect like the frontal of Membramporella. In other examples many zooecia are re- generated ; in one case a normal zocecium succeeds a normal zocecium and a double row of spines results; in another case an avicularium replaces a zocecium, but in a totally inverted position. Occurrence.—Middle Jacksonian (Castle Hayne limestone) ; Wil- mington, North Carolina (very rare). Type.—Qai. No. 62574, U.S.N.M. OGIVALINA, new genus. Endozooecial ovicell. Granular cryptocyst. No dietellae. No spines. Genotype.— OgivaXina eximipora^ new species. The zooecia have the usual aspect of those in the family Onychocellidae, but the interzooecial onychocellarium is replaced by an interopesial avicularium. In addition to the genotype this genus is represented by a new species and a new variety froni the Middle Jacksonian of North and South Carolina.
EARLY TERTIARY CHEILOSTOME BRYOZOA. 17 OGIVALINA EXIMIPORA, new species. Plate 2, fig. 1. DescHjJtion.—The zoarium is composed of one or more lamellae and incrusts pebbles or creeps over algae. The zooecia are large, elongated, ogival, distinct, separated by a threadlike ridge; the mural rim is indistinct, thin, flat, smooth, enlarged at the base into a concave, granular, irregular cryptocyst. The opesium is oval, entire, unsymmetrical in its proximal part. The endozooecial ovicell is a distal convexity, quite apparent. The avicularium is interopesial, triangular, relatively small, and without pivot. Measurements.—Upesia \ -, ^ k - a ^-a , „ . f^(?=0.75-0.80mm. ^ ?«9=0.5o-0. ( mm. I . fZs= 1.20-1.25 mm. Zooecia , ^ ^^ Length of avicularium=0.40 mm. Variations.—The opesium has little regularity of shape on account of the very irregular development of the cryptocyst itself. Although the latter is generally plainly visible, there are, nevertheless, zooecia which are almost devoid of the cryptocyst. But the most important variation is the unsymmetrical shape of its distal border, a lack of symmetry characteristic of the genus Onychocella. We know that this phenomenon is occasioned by the obliquity of the polypide in the zooecium by reason of the attachment of the retractor muscles in one of the proximal corners of the said zooecium. This anatomical feature app)ears to have more importance than the absence of the onychocellarium. Occurrence.—Middle Jacksonian: Wilmington, North Carolina (rare). Near Lenuds Ferry. South Carolina (very rare). Eich Hill, Crawford County, Georgia (very rare). Type.—Qid. No. 62575, U.S.N.M. MEMBRENDOECIUM, new genus. (Abbreviation of Membranipore with endozooecial ovicell.) Ovicell endozooecial. Small simple interopesial avicularia. Die- tellae present. No spines. Genotype.—AmpMblestrum papillatum Busk, 1884. MEMBRENDOECIUM PYRIFORME, new species. Plate 2, fig. 2. The zoarium incrusts bryozoa or small shells. The zooecia are very elongate, oval, distinct, and have a gj'^mnocyst ; the mural rim is 52091°—17 2
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U. S. NATIONAL MUSEUM BULLETIN 96 P
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American Tertiary Cheilostome Bryoz
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U. S. NATIONAL MUSEUM American Tert
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Acanthionella (Escharifora) typica
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imperati, Schizellozoon (Retepora)
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INDEX. 87 Page. Tubucella 62 ( Esch
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Bulletin - United States National Museum - Smithsonian Institution

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