49 



Basals form a sbort subhexagoual disc, gently concave below for 

 tilt' attachment of tiie column, and pierced hy a round or slightly 

 ciiHUie foil opening for tlie columnar canal. First radials large, 

 of uiuHjual size, rapidly expniidiiifi to the lateial angles, one-half 

 wider than higher, three hexagonal and two heptagonal; the two 

 hexagonal plates adjoining the azygous area are smaller than the 

 others. Second radials about two-thirds the size of the first and 

 of unequal size and shape; the one opposite the azygous area is 

 quadrangular, and twice as wide as high, and anchylosed with the 

 third radial, so the suture is very indistinct in our specimen. 

 The others are more or less distinctly hexagonal, depending upon 

 the truncation of the superior lateral angles, by the adjacent in- 

 terradials; some of the angles are broadly truncated, and others 

 barely touched. The second radials are much more convex longi- 

 tudinally than the first, which gives the calyx at this place a 

 marked pentagonal outline. The third radials are of very unequal 

 size, smaller than the second, from one and a half to two and a 

 half times as wide as high, pentagonal, axillary, and have the 

 superior angles directed almost horizontally, and from these plates 

 upward the rays are all directed horizontally. The thii-d radial on 

 the right of the azygous area bears upon each upper sloping side 

 a single secondary radial which is short, wide, pentagonal and 

 axillary, and bears upon each upper sloping side at least three 

 tertiary radials before the arms are free from the plates of the 

 vault. This arrangement gives to this ray four arms. The third 

 primary radials in each of the othei' four radial series bear upon 

 the left upper sloping side a single secondary radial, which bears 

 upon its upper sloping sides at least three tertiary radials, but the 

 other sloping side of the third I'adial bears only secondary radials, 

 which gives to each of these four radial series three arms. The 

 species, therefore, possesses sixteen arms before they become free 

 from the plates of the calyx and vault. The arms consist of a 

 single series of transverse plates, but we know nothing of what 

 bifurcations, if any, take place. The plates of the vault and in- 

 terradial areas cover the top and sides of these horizontal exten- 

 tions of the secondary and tertiary radials, leaving the interradial 

 areas deeply depressed between them. 



The first regular interradial, in each area, is a large plate that 

 rests between the superior sloping sides of the first primary radials, 

 separates the second primary radials, and sujjports upon its upper 

 —6 



