THE CRINOIDEA 



181 



biserial arms ; with cup- bowl- or saucer-shaped, composed of stout plates, 

 RR having muscle-fossae gradually more pronounced ; with x always, and 

 RA usually, present in cup, RA often supporting rt (Fig. C.). There is 

 much confusion in the nomenclature of this and allied families, and the 

 following names may not be used in what will ultimately prove the correct 

 sense. Genera Cromyocrinus, Trautschold (1867), and Eupachycrinus, 

 Meek & Worthen (1855, em. W. & Sp., 1886), Middle and Upper Car- 

 boniferous, Europe and N. America, are closely allied ; x, RA, and rt in 

 anal area. Ayassizocrinus, Shumard ex Troost MS. (1853 ; syn. Astylocrinus, 

 C. F. Roemer), Kaskaskia group, N. America, is a Cromyocrinus that loses 

 its stem in adult life, while IBB fuse to a solid mass (cf. Edriocrinus, 

 p. 191). Tribrachiocrinus, M'Coy (1847, redescr. R. Etheridge, fil., 1892 ; 

 syn. Pentadia, Dana, pars'), Permo-Carboniferous, Australia, has 1. and r. 



Krisocrinus. FIG. C. Tribrachiocrinus. 



Analyses of cups of Graphiocrinidae, Cromyocrinidae, and Eucrinidae. 



pairs of IBB fused ; single arms borne by ant., r. post., and 1. post. 

 RR ; whether the other RR bore arms is a moot point. Phialocrimis, 

 Trautschold (1879, em. R. Etheridge, fil., 1892, non Eichwald ; syn. 

 Pentadia, Dana, pars), Permo-Carboniferous, Australia, Russia, India ; 

 differs from Aesiocrinus and Ceriocrinus in little but greater thickness of 

 cup-plates, especially RR, and has, as they, only x in cup. Ulocrinus, 

 Miller & Gurley (1890), Upper Carboniferous, N. America, has large 

 RA, but very small .?, which rises partly above level of RR (Fig. XXIX.). 

 From these genera we pass almost insensibly to : FAMILY 8. ENCRINIDAE. 

 Dendrocrinoidea with forked, pinnulate, biserial arms, saucer-shaped cup, 

 with stout plates and well-developed muscle-fossae ; with no anals in cup, 

 and with sac diminished or absent (Fig. C.). Genera Sternmatocrinus, 

 Trautschold (1867), Upper Carboniferous Limestone, Russia, has IBB fused 

 into one. Erisocrinus, Meek and Worthen (1865), Lower to Upper Car- 

 boniferous, N. America, has 5 small IBB covered by the stem, and x rests 

 on upper surface of adjacent r. and 1. post. RR. Encrinus, C. F. Schulze 



