198 



ECHINODERMATA— PELMATOZOA 



PHYLUM IV 



and elevated ; anus eccentric. All bifurcations beyond costals given oft' from 

 every alternate brachial. Lower Carboniferous (Lower and Upper Burlington) ; 

 North America. 



Strotocrirms M. and W. Interbrachials not connecting with tegmen. 



an 



D 



m^ 





cfol) 



%f 



CoD 



/-CM 



6f 





BE 





Fro. 290. 



A, Ccictocrinus proboscidiali'' (Hall). Lower Carboniferous ; Burlington, Iowa. Calyx with fractureil 

 tegmen, showing the subtegniinal ambulacral skeleton, and the convoluted digestive organ. B, Enlarged 

 portion of the anibulacral skeleton. C, Natural cast of tegmen of Phy.ictocrinii.-<, with impressions of food- 

 grooves (rt), conducting fi'om the arms to the mouth (o) ; an, Anus. D, Diagram of Actmorriuus (after W. 

 and Sp.). 



Calyx not lobed ; rays bifurcating on alternate brachials from distichals up, 

 and extended into a broad, flanging rim, as in Teliocrimis, but more 

 pronounced. Arms very numerous and slender. Tegmen low, sometimes flat 

 or concave, composed of innumerable small pieces ; anus eccentric. Lower 

 Carboniferous (Upper Burlington) ; North America. 



Family 9. Platycrinidae Roemer. 



Monocyclic. Brachials and interbrachials usually hd slightly represented in the 

 dorsal cup : the lower brachials taking more or less the form of arm plates, but being 

 strongly connected, either tvith the solid tegmen by modified covering plates and strong 

 interambidacrals, or with the cup hy large interbrachials which are usually more or 

 less interambulacral in position, lladials in contact all around, there being no 

 special anal plate. Basals forming a pentagon ; three, unequal, and frequently 

 anchylosed. Silurian to Carboniferous. 



