124 ECHIXODERMATA PELMATOZOA SUB-KINGDOM in 



type from which both the Blastoids and Crinoids have been derived, neverthe- 

 less, it is expedient to treat of the Crinoids first, since a knowledge of the 

 anatomy in recent forms is essential to an adequate conception of the extinct. 



Class 1. CRINOIDEA. Miller, Sea-lilies. 1 

 (Brachiata, Bronn ; Actinoidea, F. Eoemer.) 



Usually long-stalked, more rarely non-pedunculate and sessile, occasionally free- 

 swimming Pelmatozoa with calyx composed of regularly arranged plates, and provided 

 with well-developed movable arms. 



The Crinoid organism consists of three principal elements calyx, arms, 

 and stalk. The calyx and arms together are sometimes spoken of as the 

 crown, as contrasted with the peduncle. 



1. The Calyx. The calyx has usually the form of a cup-, bowl-shaped, or 

 globular capsule, within w^hich the more important organs are enclosed. Its 

 lower (dorsal or abactinal) surface commonly rests upon a peduncle (Fig. 219) ; 

 but in some forms it is attached directly by the base, and in rare instances it is 

 free. The superior (ventral or actinal) surface is either membraneous or plated ; 

 it carries the mouth and ambulacral grooves, and hence is homologous with the 

 under side of a star-fish or sea-urchin. As a rule, only the inferior and lateral 

 portions (dorsal cup) of the calyx are visible, owing to the concealment of the 

 summit by the arms. The cup is constituted of two or more circlets of plates, 

 which are uniformly oriented with reference to the ambulacral organs. 



a. By the base is understood the one or two rings of plates intervening 

 between the topmost joint of the column and the first cycle of plates situated 

 in the projection of the ambulacra or arms. When the basis is monocyclic 

 (Fig. 220) the position of the proximal ring of plates is interradial ; but when 

 dicyclic it is radial, and the upper ring corresponds with the basals of mono- 

 cyclic forms. 



In the nomenclature of P. Herbert Carpenter, the upper series of plates in 



1 Literature : 



Miller, J. S., A Natural History of the Crinoidea or lily-shaped Animals. 1821. 



Millie/; ,/.,Ueber den Ban des Pentacrinus cuput medusae (Abhandl. Berliner Akacl.), 1841. 



de Koninck, L. 6-'., et le Hon. H., Recherches sur les Crinoide.s du terrain carbonifere de la Belgique. 

 Brussels, 1854. (Very extensive bibliography.) 



Be I/ rich, E., Die Crinoideen des Muschelkalks (Abhandl. Berliner Akad.), 1857. 



Schultze, L., Monographic der Echinodermen des Eifler Kalks (Denkschrift der k. k. Akad. der 

 Wissenschaften), Vienna, 1866. 



Sltu/nard, B. F., Catalogue of Palaeozoic Echinodermata of North America (Trans. St. Louis Acad. 

 Sci. vol. II.), 1868. (Very complete bibliography.) 



Carpenter, W. B., On the Structure, Physiology, and Development of Antedon rosaceus (Philo- 

 sophical Transactions Royal Society, vol. CLVL), 1876. 



Wachsnndh, C., and Springer, F., Revision of the Palaeocrinoidea. I. III. (Proc. Acad. Nat. Sci. 

 Philad.), 1879-86. 



Wachsmnth, C., and Springer, F., Discovery of the Ventral Structure of Taxocrinus and Haplocrinus, 

 ibid., 1888. 



Wachsmuth, C., and Xjiriiv/er, F., The Perisomic Plates of Crinoids, ibid., 1890. 



Wachsmuth, C., and Springer, F., The Crinoidea Camerata of North America. (In preparation.) 



Loriol, P. de, Paleontologie Francaise. Crinoides Jurassiques, I. II., 1882-89. 



Neumayr, J/., Die Stamme des Thierreichs. Band I., 1889.- 



Af/assiz, A., Calamocrinuq Diomcdae (Memoirs Museum Comp. Zool. vol. XVII.), 1892. 



Bather, F. A., British Fossil Crinoids (Ann. and Mag. Nat. Hist. (6th ser.), vols. V. VII.), 1890-92. 



Bather, F. A., The Crinoidea of Gotland (K. Svenska Vetensk. Akad. Handlingar, vol. XXV.), 1892. 



