150 



ECHINODERMATA— PELMATOZOA 



PHYLUM IV 



Order 1. AMPHORIDBA Haeckel {pars). 

 No radial symmetry in food grooves or calyx plates. 



Family 1. Aristocystidae Neumayr. 



Calyx composed of numerous plates without regulär arrangement. No extension 

 a of food-grooves or brachial processes. Stern undeveloped, 



or very short. Cambrian to Silurian. 



Pilocystites, Lapillocystites and Acanthocystites Bar- 

 rande. Cambrian ; Bohemia. These are obscure genera. 

 Aristocystites Barr. (Fig. 234). Calyx bursiform 

 or ovate ; ventral surface with four apertures ; stem- 

 less. Ordovician ; Bohemia. 



Deutocystites Barr. Ven- 

 tral surface with three aper- 

 tures. Calix Eouault (Cra- 

 terina Barr.). Conical, trun- 

 cate. Baculocysfites Barr. 

 Ordovician ; Bohemia. 



Megacystites Hall (Holocystis 

 S. A. Miller). Elongate, 

 cylindrical or sub-cylindrical ; 

 short - stemmed or stemless, 

 with subcentral mouth. Silur- 

 ian ; North America, Gotland. 

 Said to be a sponge. 



Aristocystites boJiemicus] Barr. Ordovician (Dd'^) ; Zahorzan 

 Bohemia. a, Side view ; b, Summit aspect (after Bariande). 



? Lodanella Kayser. Devonian ; Germany. 



Family 2. Anoraalocystidae Meek. 



Calyx oval, more or less compressed, with dissimilarly plated hroad sides. 

 either imperforate or with simple pores ; pore-rhomhs ahsent. 

 Food-grooves extended in one or more processes. Stem short, 

 tapering, of polymeric columnals. Cambrian to Silurian. 



Trochocystites Barr. (Trigonocystis Haeckel). Calyx 

 strongly compressed. Plates of the right and left sides 

 large, those of both the anterior and posterior small, 

 polygonal. All plates perforate, but without pore- 

 rhombs. Ventral surface with three apertures. Stem 

 composed of several vertical rows of plates. Cambrian ; 

 Bohemia, Spain, Northern France. 



Mitrocy Stiles Barr (Fig. 235). Like the preceding, 

 except that one side of the calyx is composed of toler- 

 ably large, and the other of small plates. Ordovician ; 

 Bohemia. 



Mitrocy Stella, Rhipidocystis Jaekel. Ordovician ; 

 Bohemia. 



Änomalocy Stiles Hall (Ateleocystites Bill.; Platycystis 

 S. A. Miller ; Enopleura Weth.). Calyx plates smaller 



Plates 



Mitrocystites mitra Barr. 

 Ordovician ; Wosek, Bohemia. 

 Snpposed right side (after 

 Jaelcel). 



and more numerous 



on the convex side than on the concave. Anus situated very low down on 



