. Bulletins of American paleontology. 256 Bulletin 267. 5 10 15 20 25 mean acanthopores per 1-mm square Text-figure 20. — Histogram of mean acanthopores per l-mm square in Amplexopora iv'inchclli Ulrich based on counts made on 59 zoarial fragments from the lower Chickamauga Group of Wills Valley, Alabama. at which point the curvature locally becomes noticeably greater. New zooecia are intercalated throughout the entire immature zone. Mature zooecia are irregularly subrounded polygonal in cross-section. Mature zooecial diameters average mm by mm, and cor- responding zooecial tube diam
. Bulletins of American paleontology. 256 Bulletin 267. 5 10 15 20 25 mean acanthopores per 1-mm square Text-figure 20. — Histogram of mean acanthopores per l-mm square in Amplexopora iv'inchclli Ulrich based on counts made on 59 zoarial fragments from the lower Chickamauga Group of Wills Valley, Alabama. at which point the curvature locally becomes noticeably greater. New zooecia are intercalated throughout the entire immature zone. Mature zooecia are irregularly subrounded polygonal in cross-section. Mature zooecial diameters average mm by mm, and cor- responding zooecial tube diameters are mm by mm. Di- aphragms are crowded at proximal zooecial tips, where they average nine per mm, which is slightly greater than the mature diaphragm spacing. Where immature zooecia have reached their full diameter, diaphragms are spaced one or more, in most places two to four, tube diameters apart. Diaphragms in the immature zone are thin, typically planar, and oriented perpendicular to the zooecial axis, but a few are slightly domal and tilted or tilred up to 45° with respect to the zooecial axis. Diaphragms in the mature zone average six per mm. Mature zone diaphragms are slightly thickened and repre- sent an extension of a group of wall laminae. Diaphragms in the mature zone are mostly planar and normal to the zooecial axis, although a few are slightly domal or concave and some are slightly tilted. Walls thicken gradually at the base of the mature zone. Mature wall thickness averages mm. Thin immature walls appear to be continuous with a thin, dark divisional line in the mature zone. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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