33 



This species might be referred to Actinocriniis, as it is abouf on 

 the dividing line between that genus and Steganocrinus. The posi- 

 tion of the plates preserved indicates that the arms were rigid and 

 directed horizontally, and it is for that reason alone that we refer it 

 to the latter genus. 



Found by K. A. Blair in the Burlington Group, near Sharon, in 

 southwestern Missouri, and now in the collection of S. A. Miller. 



STEGANOCRINUS ALBERSI, 11. S|). 



Plate II, fig. 13, azygous si<ic;Ji</. 14, opposite view; fig. to, sum mil 

 view; fig. 16, basal view. 



Species medium or below medium size. Calyx obpyramidal, mod- 

 erately truncated, pentagonal as seen from above or below. Plates 

 thick, radiately sculptured, and the Larger ones bear central nodes. 



Basals form a short, sculptured, hexagonal cup. notched at the 

 sutures and having an hemispherical depression for the attachment 

 of the column. First primary radials very large, about as wide as 

 long, three hexagonal, two heptagonal. Second primary radials less 

 than half as large as the first, rather wider than long, hexagonal. 

 Third primary radials smaller than the second, pentagonal, axillary, 

 and support on each upper sloping side a single secondary radial, 

 which is axillary, and beyond which the plates are not preserved in 

 our specimen. There are twenty ambulacral openings to the vault. 



The interradial areas all graduate up into the vault and over the 

 ambulacral channels so as to leave no dividing line between the vault 

 and the calyx. The regular interradial areas are not uniform. The 

 first plate is followed, in each area, by two plates in the second range, 

 which connect with the plates covering the sides of the ambulacral 

 channels and with the plates of the vault. In the azygous area the 

 first plate is in line with the first primary radials, but somewhat 

 smaller. It is followed by two plates in the second range and these 

 by four in the third range that unite with the plates of the vault and 

 those covering the ambulacral channels. 



The vault is only slightly convex and bears a central proboscis. 

 It is covered with convex and nodose polygonal plates. 



This species is distinguished from S. sharonensis by the character 

 of the surface ornamentation, by having proportionally larger plates 

 and fewer plates in the azygous and regular interradial areas. It is 

 very clearly a true Steganocrinus. 



