48 



and subcqual in size. Second primary radials quadrangular 

 and nearly as long as wide. Third jirimary radials expand 

 very slightly and arc about the sizt; of the second ]iriinary 

 radials. They are i)entagonal, a.xillary, and the ray ojiposlto 

 the azygous area bears upon each upper sloping side a single 

 secondary radial which is a.Killary and bears upon each upper 

 side two tertiary radials which gives to this ray four arms. 

 Tn one of the lateral rays the t.iird pi-iniury radial sa])ports on 

 each upper slojjing side two secondary radials which gives to 

 it only two arms. In the rays on each side of the azygous 

 area and in one of the lateral rays the third primary radial 

 supports upon one of its superior lateral sides three secondary 

 radials and upon the other a single secondary radial, which is 

 axillary and supports upon each upper sloping side two ter- 

 tiary radials, which arrangement gives to each of these three 

 rays three arms. There are, therefore, fifteen ' arms in this 

 species. In the rays adjoining the azygous ai'ea the proximal 

 sides of the the third primary radials support the three sec- 

 ondary plates and each distal side supports the single second- 

 ary radial that bears the tertiary soi-ies. The arms are com- 

 posed of a single series of rounded cuneriform plates. 



The interradial areas kvc substantially alike and the azygous 

 ai'ea can hardly be distinguished from them. Tli(> tii-st inter- 

 radials are the largest plates in the calyx and have nine sides. 

 They ai"e bi'oadly truncated for the second interradials. The 

 second interradials are not half as large as the first, and each 

 one is followed by a much smallei' plaf(> in the third range 

 that united with two plates belonging to the vault. 



The vault is quite convex, sharply elevated over the ainbu- 

 lacral canals, and deeply depressed in the intiu-amlndacral areas 

 toward the margin. The sutures ai-e partly destroyed in our 

 specimens, so the plates cannot be distinguished, and the sur- 

 face is more or less eroded and hence these features are not 

 shown in the illustrations. Each plate over the junction of the 

 ambulacra! canals bears a strong sharp node. Tiie azygous 

 oritice is .somewhat elevated t)ver the central ])ai-t, of live vault. 

 There is a small ovarian apei-ture clos(> to \ho amhulaci-al 

 orifice on each side of each pair of arms and on each side of each 

 single arm, which gives to the si)eci(>s eighteen ovarian aper- 

 tures. 



