162 



ECHINODERMATA PELMATOZOA 



SUB-KINGDOM III 



the M. Radianal wanting. Costals one or two ; the lower one frequently 

 extended into a spine. Arms ten, short and heavy, uniserial or biserial. 

 Kaskaskia Group and Coal Measures ; Mississippi Valley. 



Phialocrinus, Trautsch. Construction of anal area as in Graphiocrinus, but 

 the mode of articulation between radials and brachials as in Encrinus. 

 Ventral sac small. Costals two; arms ten. Accompanies the preceding, 

 and found also in Carboniferous Limestone of Russia. 



Ulocrinus, Miller and Gurley. Dorsal cup globular or cup-shaped. IB 

 projecting beyond the column. B large ; the posterior one variable in size, 

 but hexagonal like the others. IRA absent ; EA large, occupying the full 

 height of the R, and supporting the ventral sac. Arms unknown. Coal 

 Measures ; North America. 



Erisocrinus, M. and W., and Stemmatocrinus, Trautsch., are without either 

 IRA or radianal. The former has five minute infrabasals, which are covered 

 by the stem ; those of Stemmatocrinus are large and perfectly anchylosed so as 

 to form a single plate. Certain Coal Measure species 

 of Erisocrinus are scarcely distinguishable from Encrinus 

 liliiformis. Sub - Carboniferous and Coal Measures ; 

 North America and Russia. 



[Encrinus, Miller. The description of this genus is 

 retained in its original position under the ArticulataJ] 



Family 10. Agassizocrinidae. 

 "Wachsmuth and Springer. 

 (Astylocrinidae, Roemer.) 

 Base dicyclic. Dorsal cup elongate, 

 with massive plates, and enclosing an 

 extremely narrow visceral cavity. Infra- 

 Nasals and la-sals very large ; the former 

 consisting of five elongate pieces, which 

 form an almost solid semiovoid or semi- 

 globose body. Radials very short, and 

 proportionally smaller than the other 

 plates of the cup. Anal and radianal 

 both present. Structure of tegmen and 

 ventral sac unknown. Arms ten. Sub- 

 Carboniferous. 



Agassizocrinus, Troost (Astylocrinus, 

 Roemer), (Fig. 268). There is evi- 

 dence that this form was fixed in its 

 early stages by a stem, but subsequently became free-swimming. In the 

 adult condition the scar where the column was attached, as well as the 

 suture lines between the IB, became gradually obliterated by a secretion 

 of calcareous matter over the whole surface of the plates. Restricted to 

 the Kaskaskia Group of North America. 



[Reference may be made here to Jaekel's recent Monograph, "Beitriige zur Kenntniss der 

 palaeozoischen Crinoideen Deutschlands " (Palaeont. Abhandl. von Dames und Kayser, ncue 

 Folge, Bd. III.), 1895. Unfortunately this excellent memoir was not available before the 

 present sheet was in print. TRANS.] 



FIG. 268. 



Agassizocrinus laevis, 

 Koeiner sp. Kaskaskia 

 Group; Indiana, a, Crown, 

 nat. size; b, Ventral aspect 

 of the coalesced infrabasal 

 disk; c, Side-view of same, 

 nat. size (after M. and W.) 



Scaphiocrinus multiplex, 

 Trautsch. Upper part of 

 Sub-Carboniferous ; Mos- 

 cow, Russia. Nat. size. 



