50 



Basal concavity pentagonal, funnel shaped, and without orna- 

 mentation. Basal plates form a hollow cone within the calyx, 

 into which the end of the column is inserted. First primary 

 radials as long as wide and abruptly bent in the middle, the 

 lower part forming part of the funnel-shaped columnar cavity, 

 and the superior end curving as abruptly upward. The plates 

 are pyramidal, with the apex at the center, and radiately sculp- 

 tured. A furrowed ridge extends from the apex of one plate 

 to the next, which forms the pentagonal outline of the basal 

 concavity and on which the calyx will rest if placed on a 

 level surface. Second primary radials quadrangular, about 

 one-fourth wider than long and sides nearly parallel. Third 

 primary radials smaller than the second, one-half wider than 

 long, pentagonal, axillary, and in four of the rays support 

 on each upper sloping side two secondary radials, which gives 

 to each of these rays two arms. In the ray adjoining the 

 azygous area on the right the third primary radial supports 

 on the proximal side three secondary radials, and on the dis- 

 tal side of a secondary radial that is axillary and supports 

 upon each upper sloping side two tertiary radials which gives 

 to this ray three arms. There are, therefore, eleven arms in 

 this species. The arms are composed, at the base, of a single 

 series of plates. 



In the regular interradial areas there are only two plates, 

 but the azygous area is wider in the superior part and con- 

 tains three plates. The first interradials are large, pyramidal 

 and radiately sculptured. The second plate is quite small, not 

 more than one fourth as large as the first and it connects with 

 two plates belonging to the vault. The first azygous plate is 

 like a regular first interradial and is followed by two plates 

 in the second range that unite with three plates belonging to 

 the vault. 



The vault is sharply elevated over the ambulacral canals and 

 deeply depressed in the interambulacral areas. The azygous 

 orifice is elevated at the central or subcentral part of the vault, 

 but can hardly be said to be at the summit of a proboscis. 

 The vault is covered with polygonal plates, which, in our 

 specimens, show no surface ornamentation. The ovarian pores 

 appear to be within the last plates belonging to the calyx, 



