CRINOIDEA. 



297 



crinus Goldf. (Ctenocrinus Bronn), Xenocrinus Miller, Patelliocrimis 

 Ang., Glyptocrinus Hall, Corymbocrinus Ang. (Polypeltes Ang). Stelidio- 

 crinus Ang. (Harmocrinus Ang.). 



Fam. 9. Calyptocrinidae. 

 Monocyclic. Calyx regular, 

 composed of 4 basals, 5 

 radials in contact, 2x5 primi- 

 brachs, 5 secundibrachs ; all 

 interradii alike. Arms 20, 

 biserial. Silurian, Devonian. 

 Callicrinus Ang., Eucalypto- 

 crinus Goldf., Hypanthocrinus 

 Phill. 



Order 4. FLEXIBILIA. 

 Calyx cover flat, flexible, 

 with loosely arranged inter- 

 ambulacral plates. Ambu- 

 lacra with alternating cover- 

 ing plates, their calycine por- 

 tions apparently not covered 

 by interambulacral plates 

 (Fig. 195). Mouth central, 

 open, surrounded by 5 orals. 

 Anus excentric. Dicyclic, 3 

 or 5 small infrabasals, often 

 hidden by top joint of 

 stalk. The calyx extends to 



the lower brachials (primibrachs, secundibrachs and sometimes terti- 

 brachs being included) and the brachial plates of the calyx are united by 

 articulation, not by suture. The brachials incorporated in the calyx 

 are either in contact laterally or separated by interradials extending to 

 the basals or first radials. A single azygos (anal) plate sometimes present 

 in the posterior interradius. Arms strongly branched distallv, uniserial 



CO 



FIG. 203. Taxocrinus splendens Mill, and Gurley 

 (from Lang), ir, ?>i, i>9 interradials, di secundi- 

 brachs (distichals), ba basals, ib infrabasals, co 

 stalk, r radials, ci, 02, 03 primibrachs (costals). 



FIG 204. Marsupites testudinarius Schloth. (after Zittel). a calyx, nat. size ; b radial with 

 the first arm segment ; c upper part of arms. 



with or without pinnules. All brachialia with dorsal canal (except some- 

 times in the distal brachials), and united by articulation. U. Cambrian to 

 Carboniferous. 



