CRINOIDS IN SECONDARY STRATA. 



487 



crinus, Plicatocrinus, Apiocrinus, Miller icrinus, Solanocrinus ; to- 

 gether with Antedon, Actinometra, and Saccocoma, 1 the former of 

 which still survive, and the last ranges to the Chalk. 



Fig. 96. Encrinus. Fig. 97. Pentacrinus. 



Another cretaceous genus is Torynocrinus. Bourguetocrinus (fig. 

 98) ranges to the Tertiary. Marsupites and Uintacrinus are also cre- 

 taceous. The Tertiary Crinoids almost all belong to existing genera. 



Fig. 99. Apiocrinus. Fig. 100. Torynocrinus,- 



Cystoidea are an extinct group of Echinoderms limited to the 

 Primary rocks. They have a more or less globular body formed of 



1 See P. H. Carpenter, Q. J. G. S., vol. xxxvi.-viii. 

 , 2 An. Nat. Hist., March 1866. 



