196 



ECHINODEEMATA— PELMATOZOA 



PHYLUJI IV 



tube rather lai'ge, extending beyond arms. Arms twelve to sixteen. Upper 

 Burlington and Keokuk Gr. ; America. 



Dizygocrinus W. and Sp. Calyx rotundate. Anal tube rather small, 

 usually not extending beyond the arms. Arms single or double, from twelve 

 to twenty openings. Upper Burlington to St. Louis Group ; America. 



Eutrochocrinus W. and Sp. Calyx wheel-shaped. Anal tube long. Arms 

 short, either single or double from twenty openings. Upper Burlington and 

 Keokuk Group ; America, 



y. Interlrachials few, sometimes connected with tegmen all around. 



Uperocrijiii'S Meek and Worthen (Lobocrinus W. and Sp., Hyperocrimis 

 Bather) (Fig. 297). Calyx pyriform. Anal tube large 

 and often spiniferous. Arms short, single, often arranged 

 in groups, openings directed upward. Upper Burlington 

 and Keokuk ; America. 



§ 2. Anus ivithout a tube, directly through tegmen. 

 Interbrachials few, usually not connecting with tegmen except 

 at anal side. 



Aorocrinus W. and Sp. Calyx small, elongate to ro- 

 tund or biturbinate. Arms 

 rather strong, onefrom each 

 opening, cylindrical. Teg- 

 men plates not spiniferous. 

 Devonian to Burlington ; 

 Europe and America. 



Coelocrinus M. land W. 

 {Sphaerocrinus M. and W. 

 non Roemer). Similar to 

 preceding genus, but with 

 concave base. Burlington 

 Group ; America. 



Dorycrinus Roemer (Fig. 



var. im<ermerfiM.s(M. and W.). Lower Ayb). OalyX Small tO hxrge; 

 Carboniferous ; Burlington, Iowa. „„„<.„,„• i ^ -.i 



Calyx viewed from the anal side. pOSteriOr Oral aloue, Or With 



Natural size (after Meek and Wor- primary radial plates of 



tegmen, spiniferous. Arms 

 rather small, usually two from each opening. Devonian to Keokuk ; America. 

 Agaricocrinus Hall (ex Troost). Calyx small to large, hemispherical, with 

 dorsal side usually flat or concave, and greatest height above the arm bases. 

 First primibrach sometimes hexagonal. Arms ten to sixteen, very heavy, 

 directed outwards. Burlington to Keokuk ; America. 



Fig. 297. 



Pig. 2'.)S. 

 Dorycrinus quiwiuelohus (Hall) 



Uperonrinus 'pyrlforinis 

 (Shumard). Lower Carbon- 

 iferous ; Burlington, Iowa. 

 Nat. size (after Meek and 

 Worthen). 



Family 8. Actinocrinidae. 



Monocyclic. Loiver brachials, with well-defined interbrachials between them, 

 forming an important part of the dorsal cup. Radials in contact except at the anal 

 side, where they are separated by a hexagonal anal plate, followed by two plates in the 

 second range. Basals three, forming a hexagon. Arms biserial in all known genera. 

 Rays usually branching by alternate bifurcations. Lower Carboniferous. Kinder- 

 hook to Keokuk. 



