204 ECHINODERMATA— PELMATOZOA phylum iv 



rhombic, obliquely below r.post.R. IBr one to four. Silurian ; Gotland, 

 Enghuid, and North America (Niagara of Avestern area and of New York). 



Niptevocrinns Wachsmuth, in Meek and AVorthen. Similar to Fycnosaccns, 

 but without RA or anal x, and with infrabasals fused to one. The last 

 survivor of this family. Lower Burlington to Keokuk ; Mississippian area, 

 North America. 



Family 2. Sagenocrinidae Springer. 



Infrabasals abutting on dorsal side of basals, low and flat, taking little part in 

 calyx wall. Croivn usually large, elongate, expanding above the radials. Hays 

 above radials partly or wholly separated all aroicnd. Silurian to Lower 

 Carboniferous. 



Temnocrinus Springer. Arms dichotomous. Anals and iBr only in lower 

 part of interradial areas ; anals more than one abreast. BA in form of B 

 under 'r.post.R. Anal x separating BR and touching post.B. IBr two. 

 Type, Taxocrinus tuberculatus Miller. Silurian ; England, (?) North America. 



Meristocrinus Springer. Similar to Temnocrinus, but with anal x followed 

 by other plates in series, and IBr three. Type, Taxocrinus loveni Angelin. 

 Silurian ; Gotland. 



Sagenocrinus Austin. Arms dichotomous. Anal and iBr areas filled with 

 solid plates. RA obliquely below r.post.R, usually between BB, and not 

 touching r.ant.R. IBr two. Silurian ; England, Gotland, and North 

 America (Western Niagara). 



Lithocrinus W. and Sp. (Forbesiocrinus Aug. non Kon.). No RA. Arms 

 heterotomous, with ten main trunks bearing branching ramules. iBr well 

 developed in lower part of areas. IBr two. Type, Forbesiocrinus divaricafus 

 Ang. Silurian ; Gotland. 



Forbesiocrinus Koninck and Lehon. No RA. Arms dichotomous. iBr 

 usually numerous, filling the areas with solid plates. IBr three, except in 

 F. agassizi, which has two. The culmination of this family. Lower Carboni- 

 ferous (Lower Burlington to Warsaw) ; Belgium. Also Mississippian area, 

 North America. 



Family 3. Ichthyocrinidae Waclismutli and Springer (restr.), 



Infrabasals wholly within the ring of basals, concealed by the column, 

 sometimes disappearing by resorption. Crown usually elongate, 

 expanding above radials, but often infolding distnlly. Arms 

 usually closely abutting or interlocking. Silurian to Lower 

 Carboniferous. 



a. Rays in contact except between posterior radials when separated 

 by anal a-. 



Ichthyocrinns Conrad (Fig. 305). Arms dichotomous, 

 closely interlocking, and infolding. RA in form of /.' under 

 icUhywrinn^ inens r.post.R. No anal, posterior basal not differentiated. IBr 

 crown? 'siiuria'".KNia two. Silurian; Gotland, England and North America (New 



Irani (Jroiiii); Luck- \t ^ i -itt i ■\t „ \ 



port, New York (after York and Western Niag;i,ra area). 



"=!")■ Clidochirus Ang. Similar to Ichthyocrinus, but with 



posterior basal difi"erentiated, supporting anal x alone, or followed by others. 



