57 



Basal plates almost covered by the column. First primary 

 radials wider than long, the two on the azygous side being 

 somewhat larger than the others. Second primary radials 

 about one half wider than long, quadrangular. Third primary 

 radials expand slightly to the superior lateral angles,, longer 

 than the second, pentagonal, axillary, and in the ray on the 

 right of the azygous area bears a single, secondary radial up- 

 on each superior, sloping side, which is axillary, and bears 

 upon each superior sloping side two tertiary radials, which 

 gives to this ray four arms. In each of the other four rays, 

 the third primary radial bears upon one upper sloping side 

 three secondary radials, and upon the other, one secondary 

 radial, which is axillary, and supports upon each upper sloping 

 side, two tertiary radials. This arrangement gives to each of 

 these rays three arms. There are, therefore, sixteen arms and 

 sixteen ambulacral openings to the vault in this species. 



The azygous area is like the others, except a little larger. 

 The first interradials are the largest plates in the calyx, have 

 nine sides, and are broadly truncated above for the second 

 interradials. The second interradials are about half as large 

 as the first, and are followed by a single plate, which is about 

 half as large as the second, and unites with two large, elon- 

 gated plates belonging to the vault. 



The vault is very slightly elevated over the radial areas, and 

 about equally as much depressed in the interradial areas. It 

 is substantially covered by three circles of plates, the surface 

 of which is covered by granules, and a few of the plates over 

 the radial areas bear a small central node, as shown in the 

 illustration. The subcentral azygous opening is slightly ele- 

 vated and surrounded by four plates, two of which form part 

 of the first circle of plates and, if counted with the first circle, 

 there are seven plates in the first circle, and without them 

 there are only five; but the circle is not complete without count- 

 ing one of them. In the second circle there* are seven 

 plates. In the third circle there are fifteen plates, two in each 

 depressed interradial area that unite with the plates of the 

 calyx and one over each radial area. These are all the plates 

 covering the vault except those over the radial areas at the 

 base of the arms. There are no ovarian openings, at least, in 

 a beautifully preserved specimen none can be discovered. 

 —8 



