21 



pore f)ii cafli side of oacli radial scries may he i)laiiily seen in tlic 

 larjjor s]H'cimcn. Iiut (inly piirt oi' them can be seen in the sperinii'ii 

 illustrated. 



Basals form a short roiin<l dis'', haviiiu^ an lieiuispherieal dejjres- 

 sion for the attachment of the column. First primary radials as 

 larjje as the second and third together, wider than Iotij;. three 

 hexagonal, two heptatifinal. Second primary radials quadrang-idar, 

 two or two and a half tinu^s as wide as Ions/. Third ])rirnary radials 

 larp;er that fh(> second, two hexa<:;onal, three pentau'onal. axillary, 

 and in the ray opj)osite the azygous area siip])r)rts, on each upper 

 sloi)iii}i' side, three secondary radials, which tjives to this ray two 

 arms. In one lateral ray the third radial bears two secondary radials 

 on each u|)]ier side, and in the other oidy one. tlu* last beinjj axillary 

 and support iuLt upon each upper side two tertiary radials. which 

 <iri\-es to each of tht'se rays four arms. In the ray ou each side of 

 the azygous area the thir<l jiriniary radial supports, on the distal 

 side, three secondary radials. and on one of the proximal sides one 

 axillary secondary radial, which bears on eacdi side two tertiary 

 radials and on the other proximal side two secondary radials. the 

 last being axillary and su|)pi)rting on each upper sitle two tertiary 

 radials. which gives to each of these rays three arms. There are. 

 therefore, sixteen ambulacn'al openings to the vault in this species. 

 The ai'ui formula is ii - •1+2-;--1t •5- 



'I'here are three i)latt's in each regvdar interradial area, one. fol- 

 lowed by two. whicdi are cut off from all connection with the vault 

 by the union of the radials above them. Theri' are only four xjlales 

 in the azygous area. The first one is in line with the first primary 

 radials and about the same size. It is followed by three plates, the 

 middle one being quite large, but cut ofT' from the vaidt by the union 

 of the tertiary radials above it. 



'I'he vault is ne.-irly as large as the calyx and i>ears a small central 

 proboscis. It is covered with convex, [xdygonal plates and is slightly 

 lobed over the ambnlacral canals. 



It is a marked species in its general appearance And nei'd not be 

 compan-d with any other sixteen-armed species to distinguish it. 



I'Viund by K. A. Blair, in the Burlington group, near Sharon, in 

 Southwestern Mi.ssouri, and now in the collect iou of S. A. Miller. 



