CLASS II CYSTOIDEA il 7/'Z/ 
Crinoidal fragments have been detected in the Cambrian, but consist of 
stem-joints only (Dendrocrinus). The Ordovician of England also yields a 
variety of stem-joints, and well-preserved calices of Hybocrinus and Baerocrinus 
occur in rocks of the same age in the vicinity of St. Petersburg. In North 
America, also, the Trenton and Hudson River limestones are locally very 
rich in Crinoid remains. The Silurian localities of Dudley and Wenlock, 
England, and especially the island of Gottland, Sweden, are famous for the 
surprising abundance and exquisite state of preservation of their fossil 
Crinoids. The Swedish forms alone comprise 43 genera and 176 species. 
The Silurian of North America, notably the Niagara Group, likewise 
contains a large variety of forms. 
The best known Devonian localities are the Eifel, Rhineland, Nassau, West- 
phaha, the Ardennes, Asturias, Departement Mayenne, and North America. 
The Carboniferous Limestone of Tournay and Visé, Belgium, and that of Eng- 
land, Ireland, and the vicinity of Moscow, Russia, is occasionally charged with 
exceptionally well-preserved Crinoidal remains. But the most famous of all 
horizons is the Sub-Carboniferous Limestone of North America, where, in 
particular, the localities of Burlington, Iowa, and Crawfordsville, Indiana, 
have acquired a world-wide reputation. 
The Permian has yielded but a single genus, which is doubtfully referable 
to Cyathocrinus. From the Trias only the Enerinidae and a few species of 
Pentacrinus are as yet known. The remaining members ‘of the <Articulata 
make their appearance in the Jura and Cretaceous, and with the exception of 
the Saccocomidae, are still represented in the existing fauna. 
Class 2. CYSTOIDEA. Leopold von Buch.! 
Extinct, pedunculate, or more rarely stemless Pelmatozoa, with calyx composed of 
more or less irregularly arranged plates. Arms imperfectly developed, sometimes absent. 
Calyx plates often finely perforate. 
The calyx is globose, bursiform, ovate, or ellipsoidal in form, more rarely 
1 Literature : 
Volborth, Alex. von, Ueber die Echinoencrinen (Bull. Acad. Imp. Se. St. Petersb. vol. X.), 1842. 
Volborth, Alex. von, Ueber die russischen Sphaeroniten (Verhandl. Mineralog. Gesellsch. St. 
Petersb.), 1845-46. 
Buch, Leopold von, Ueber Cystideen (Abhandl. der Berliner Akad. fiir 1844), 1845. Translated 
in Quart. Journ. Geol. Soc. London, 1845. 
Forbes, Edward, On the Cystidea of the Silurian Rocks of the British Islands (Mem. Geol. Survey 
Great Brit. vol. II., part 2), 1848. 
Miller, Johannes, Ueber den Bau der Echinodermen (Abhandl. der Berliner Akad.), 1853. 
Hall, James, Palaeontology of New York, vol. II., 1852, and vol. III., 1859. 
Billings, E., On the Cystidea of the Lower Silurian Rocks of Canada (Figures and Descriptions of 
Canadian Organie Remains, Decade IIT.), 1858. 
Hall, James, Descriptions of some new Fossils from the Niagara Group (20th Ann. Rept. N.Y. 
State Cabinet of Nat. Hist.), 1867. 
Billings, E., Notes on the Structure of Crinoidea, Cystidea, and Blastoidea (Sil. Amer. Journ. 
Sci. 2nd ser.), vol. XLVIII., 1869, and XLIX., 1870. 
Volborth, Alex. von, Ueber Achradocystites und Cystoblastus (Mem. Acad. Imp. Sci. St. Petersb., 
vol. XVI.), 1870. 
Schmidt, Fr., Ueber Baltisch-Silurische Petrefacten (Mém. Acad. Imp. Sci. St. Petersb., vol. 
XXI.), 1874. 
Barrande, Joachim, Syst¢me Silurien du Centre de la Bohéme. Cystidées, vol. VII., 1887. 
Carpenter, P. H., On Certain Points in the Morphology of the Cystidea (Journ. Linn. Soe. vol. 
XXIV.), 1891. 
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