. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. DEVONIAN CRINOIDS OF NEW YORK a Theca or Calyx The calyx contains the viscera of the (abactinal surface) is usually attached to a column, but sometimes the crinoid is at- tached directly by the base and more rarely it is free. The z upper (ventral or actinal) sur- > face, or tegmen, is homologous * to the under side of the starfish and bears the mouth and ambulacral grooves. (i) Dorsal cup. Most fre- quently in fossil crinoids only the lower and lateral portions of the calyx are visible, because
. The Devonian crinoids of the State of New York. Crinoidea, Fossil; Paleontology; Paleontology. DEVONIAN CRINOIDS OF NEW YORK a Theca or Calyx The calyx contains the viscera of the (abactinal surface) is usually attached to a column, but sometimes the crinoid is at- tached directly by the base and more rarely it is free. The z upper (ventral or actinal) sur- > face, or tegmen, is homologous * to the under side of the starfish and bears the mouth and ambulacral grooves. (i) Dorsal cup. Most fre- quently in fossil crinoids only the lower and lateral portions of the calyx are visible, because the arms conceal the upper por- tions. In the simplest form of 5 crinoid the dorsal cup is com- h posed of two or three circlets of plates. Those supporting the arms and constituting the most important circlet of plates are known as the radiate; the other one or two circlets constitute the base. Where there is but § one circlet of plates in the base it is known as monocyclic; where there are two, as dicyclic (figure 2). In a monocyclic base the crinoid. The dorsal cup Anal lube . -Pinnules. Figure I A simple form of crinoid: Botryocri nju s decadactylus (Wenlock limestone) seen from the posterior interradius. (After Bather, 1900). plates alternate with the radials and are called basals; in a dicyclic base the plates of the lower ring are radial and are known as the infrabasals {under-. 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 Goldring, Winifred, 1888-1971. Albany : University of the State of New York
Size: 1082px × 2309px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectpaleont, bookyear1923
