7 



Basals very short, wide, truncated below, lateral sutures deep, 

 superior face of each concave, truncated face about twice the di- 

 ameter of the column, the facet for which is only moderately 

 concave and radiately furrowed. First primary radials of un- 

 equal size, from two to • four times as wide as long, superior face 

 concave, three hexagonal, two heptagonal, and each bears three 

 nodes, one central from which the angular radial ridge arises, and 

 one on each prolonged lateral side. Second primary radials of 

 unequal size, from one and a half to two and a half times as wide 

 as long, quadrangular. Third primary radials about one half 

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

 upper sloping side, two secondary radials. The secondary radials 

 are as large as the second and third primaries. The second sec- 

 ondary radials are axillary, and, in three rays, bear upon one of 

 the superior sloping sides two tertiary radials, the second one of 

 which is axillary and bears upon each superior sloping side three 

 quaternary radials, and upon the other side of the second sec- 

 ondary radials, which are the proximal sides, four tertiary radials, 

 which arrangement gives to each of the three rays six arms. In 

 the ray opposite the azygous area and in one of the lateral rays 

 each second secondary radial is axillary and bears upon each 

 upper sloping side four tertiary radials, and consequently these 

 rays have four arms. There are, therefore, twenty-six arms in 

 this species and twenty-six ambulacral openings to the vault. 

 There are no intersecondary or intertertiary plates. 



In two of the regular interradial areas there is one large plate 

 followed by a small one, and in the other two areas there is a 

 large plate followed by two small ones. These plates are tumid 

 and each bears a central node. The azygous area is somewhat 

 trapezoidal in outline and contains seven plates. The first one is 

 in line with the first primary radials, but is much larger than 

 either of them and bears a large transverse wedge-shaped spine. 

 It is followed by three tumid, nodose plates in the second range, 

 and these, in turn, by two plates, one of which is quite small, 

 and above the larger plate, in the third range, there is a small 

 plate in the fourth range, which is immediately below the angle 

 formed by the union of the first quaternary plates. 



Vault high, broadly rounded, most tumid opposite the azygous 

 side and covered with polygonal, nodose plates. The larger plates 

 bear two, three or more nodes, but the smaller ones bear a single 

 central node. The proboscis is subcentral on the azygous side. 

 There are narrow, elongated plates at the base of the vault, be- 

 tween the plates covering the ambulacral furrows, except between 



