182 



ECHINODERMATA PELMATOZOA 



SUB-KINGDOM III 



Family 1. Aristocystidae. Neumayr. 



Calyx composed of numerous heavy plates, arranged either irregularly or in suc- 

 cessive zones, and covered on both sides by a calcareous integument. Calyx plates 

 traversed by simple canals terminating on either surface in pores distributed either singly 

 or in pairs. Ambulacral grooves subtegminal (" hydrophores palme'es ") arms want- 

 ing ; stem obsolete or very short. Ordovician. 



Aristocystites, Barr. (Fig. 298). Calyx bursiform or ovate; ventral surface 

 with four apertures. Ordovician (Etage D) ; Bohemia. 



Deutocystites, Barr. Ventral surface with three apertures. Craterina, Barr. 

 Conical, truncate. Pyrocystites, Barr. Clavate in form. All three genera in 

 Ordovician (Etage D) of Bohemia. 



FIG. 299. 



Glyptosphaerites Leuchtenbergi, Volborth. Ordovician ; St. Petersburg. 

 a, Calyx seen from above (natural size); b, Same from the dorsal face, with 

 stem attached, reduced 1/2 ( af ter Volborth) ; c, Calyx plates showing double 

 pores (enlarged). 



Aristocystites Jiohemir.us, Barr. 

 Ordovician (I'd 4 ) ; Zahorzan, 

 Bohemia, a, Side view ; b, Sum- 

 mit aspect (after Barrande). 



FIG. 300. 



Protocrinites oviformis, Eichwald. Ordovician ; Pulkowa, Russia. 

 *, Calyx viewed from above ; b, Same from below (after Volborth). 



Family 2. Sphaeronitidae. Neumayr. 



Calyx globular or cylindrical, short-stemmed or stemless, and composed of numerous 

 irregularly arranged plates with pores united in pairs. AmbulacraL grooves either 

 open or protected by covering plates, and either short and simple, or elongated and 

 branching. Arms as a rule exceedingly small and primitive. Ordovician and 

 Silurian. 



Sphaeronites, Rising. Globose, stemless. Five short ambulacral grooves 



