48 Trans. Acad. Sci. of St. Louis. 



ambulacral areas often acute and projecting beyond the sum- 

 mit. Column thin and round. Geoloo;ical range from the 

 upper Silurian to the Coal Measures. The following species 

 belons: to this genus : — 



1. CoDASTER ATTENUATUS, Lyon. Devonian. 



Cadaster attenuatus, Owen. 

 Heteroschisma alternatum, Wachsmuth. 

 Heteroschisma alternatum var. elongatum, Wachsmuth. 



2. Cod ASTER americanus, Shumard. Devonian. 



3. CoDASTER cInadensis, E. Billiugs. Devonian. 

 Cadaster hindei, Whiteaves. 



4. CoDASTER GRACILIS, Wachsmuth. Devonian. 

 Heteroschisma gracilis, Wachsmuth. 



5. CoDASTER KENTUCKYENSis, Shumard. Lower Subcarbo- 



niferous. 



Pentremites kentiickyensis, Shumard. 

 Phaenoschisma, Etheridge and Carpenter. 



6. CoDASTER PULCHELLUS, S. A. Miller and C. B. Dyer. 



Niagara gr. 

 Stephanocrinus puchellus, Miller and Dyer. 



7. CoDASTER PYRAMiDATUS, Shumard. Devonian. 

 Cadaster alternatus (pars), Lyon. 



8. CoDASTER suBTRUNCATUS, Hall. Devonian. 



Pentremites suhtruncatus , Hall. 



Heteroschisma gracile, "Wachsmuth. 



Traastocrinus suhtruncatus, Etheridge and Carpenter. 



B. Order Irregulares. 



1. Family Olivanidae. 



1. Genus Olivanites. 



General form of the body oval or round. Base very small 

 and depressed. Fork pieces very short, hardly more than -g- 

 of the whole length of the body. Ambulacra narrow, linear 

 and extending the full length of the body. Deltoids very 



