35 



STEGANOCKINUS Bl.AlIil, 11. sp. 



J'liilc J I, Fi(-i, 'J I, view opposite the azygovn aide, oil Ike arms, ex- 

 cept one, hrolx'en off at the calij.r: Ficj. 22. Iiasal view, 

 part of the sutures destroijcd. 



Species iiudiuin size, (^nlyx iini-sliaped, traiisvorse section sub- 

 pentagonal. Plates thick, radiatdy sculjitured. the larger ones hav- 

 ing a small central node. 



Basals form a subhexagonal, sculptured disc four or five times as 

 wide as high. First primary radials a little wider than long, three 

 hexagonal, two heptagonal. Second primary radials onlj' a little 

 small(>r than the first, hexagonal. Third primary radials a little 

 smaller than the second, pentagonal, axillary, and support on each 

 upper sloping side a single secondary radial, which is axillary, and 

 supports on each upper sloping side tertiary radials. Two tertiary 

 radials are ]ireserved in our specimen and there is a small plate rest- 

 ing in the angle between the two secondary radials that separates the 

 first proximal t<>rtiary radials. This species has at least twenty am- 

 bulacral openings to the vault. 



The first regular interradial in each area is followed by a range of 

 plates, two of which are directly above it and unite with the plates of 

 the vault, and upon each side of these the plates are continued out 

 u\)cm the side of the radial series and cover jDart of the ambulacral 

 channel. In the azygous area, the first plate is in line with the first 

 jirimary radials and about the same size. It is followed by two plates 

 in the second range, above which there are three plates that unite 

 with the ijlates of the v^ault and upon each side of these the lalates 

 are continued out upon the side of the radial series and cover part of 

 the ambulacral channel. 



The vault is highly convex, much elevated over the ambulacral 

 canals, and bears a large central proboscis. It is covered by convex 

 and nodose, polygonal plates. 



This species is a true Steuaiiorrlinis and very readily distinguished 

 from all that have been heretofore described. 



I'^ound by R. A. Blair, in whose honor we have proposed the sjie- 

 cifii- name, in the Burlington Group, near Sharon, in Southwestern 

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



