UKDKK IV 



CIMXOIDEA FLEXIBILIA 163 



Order 4. FLEXIBILIA. Zittel. 

 i, p.p. \V. and Sp., 1 non Miillcr ; I>'hthyocrinacea, Neumayr.) 



Base diet/die, with stem or stemless ; the proximal ring of the base in the latter 

 case enclosing a (?) dorsocentral (Carpenter). Arms branching, pinnulate or non- 

 jiiiiHuhift'. Ti'tiii/fK, .^ii fur as has been observed, composed of orals and numerous 

 exceedingly >///////, loosely united, movable pieces; orals asymmetrically arranged. 

 Month mn/ ,niilnilifi-a exposed/ the latter roofed over by covering pieces and enclosed 

 bij side-plates. Ordovician to Carboniferous, and also Cretaceous. 



Family 1. Ichthyocrinidae. Wachsmuth. and Springer. 



./// jtlates of the calyx ami of the arms from the radials upward united by loose 

 nntni-c. or by muscular articulation. Base dicyclic ; infrabasals three, unequal, small, 

 f<i r<lt/ extending beyond the column, and fused with the top stem-joint; basals five, 

 small. Radials succeeded by one to six costals, which in species without interradials 

 increase in size upwards. Brachials united by more or less waving sutures, and their 

 lower edges furnished with tooth-like projections which ft into depressions on the 

 subjacent plates ; occasionally the projections are developed as separate patelloid plates. 

 Interbrachials, when present, rather irregularly arranged. Tegmen squamous ; 

 composed of five orals and numerous, very small, movable plates. Arms non- 

 pinnulate, and exhibiting a very wide and shallow ventral groove. Column round ; 

 the upper ossicles extremely short, and generally wider than the others. Ordovician 

 to Coal Measures. 



Ichthyocrinus, Conrad (Fig. 270). IB very small; It and lower brachials 

 laterally in contact at all sides ; anals and interradials not represented. 

 Crown appearing like a perfectly solid body when the arms are closed. 

 Silurian to Coal Measures ; North America and Europe. 



Lecanocrinus, Hall (Fig. 271), Like the preceding, except that only four 

 of the rays are laterally in contact, the two posterior ones being separated 

 by a rhomboidal RA and a somewhat larger IRA. Silurian ; North America 

 and Europe. 



Taxocrinus, Phill. (Figs. 272, 273). All five R separated by inter- 

 brachials. Costals two, sometimes three. The posterior B larger than the 

 others, truncated, and supporting an IRA. This is followed by a longi- 

 tudinal row of small elongate supplementary anals, which are interposed 

 between numerous very minute irregular pieces. Plates of the four regular 

 interrays less numerous, larger, and more symmetrically arranged. Ordovician 

 to summit of Sub-Carboniferous ; North America and Europe. 



Gnorimocrinus, W. and Sp. Like Taxocrinus, but with RA in addition to 

 IRA ; the former also supporting a longitudinal row of supplementary 

 anals. Silurian; Gottland. 



OnycJwcrinus, Lyon and Gassed. Calyx depressed; arms spreading and 

 talon-like. IB rarely projecting beyond the R, and closely or only partially 



1 [The three families embraced iinder this order, the Ichthyocrinidae, Marsupitidae, and 

 Uintacrinidae, are included by Wachsmuth and Springer under the Articulata (Articidosa) as 

 redefined by them. The non-pinnulate Ichthyocrinidae, however, are placed in a separate sub- 

 order under the name of Articulata Impinnata ; while the Marsupitidae, Uintacrinidae, and most 

 of the Mesozoic and Recent Crinoids constitute the second sub-order Articulata Pinnata. TRANS.] 



