56 



diameter of the coluiun. First primary radials as long as wide 

 and entirely within the basal concavity and forming part of the 

 funnel shaped depi-ession. Second primary radials form i)ait 

 of the basal concavity, a little wider than long. f|iiudrangi)lar 

 and the calyx will rest on the central nodes of the first inter- 

 radials and these plates. Third primary radials curve upward, 

 nearly as long as wide, pentagonal, axillary, and in the ray on 

 each side of the azygous area, bear upon each upper sloping 

 side a single secondary i-adial which is axillary and bears upon 

 each upper side two tertiary radials, which gives to each of 

 these rays four arms. In each of the other three rays the 

 third primary radial bears upon one upjier 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, which gives to each of the.s(' three rays 

 three arms. Thei-e are, therefore, .seventeen arms and seven- 

 teen ambulacral openings to the vault in this species. It will 

 be observed that the arm formula is the same that is found in 

 D. bellulus. 



The interradial areas ai"e not alike, in this species, and the 

 azygous area is smallei- than eitlier of tiiree of the others. 

 The tirst intei-radials are tlio largest plates in the calyx, the 

 lower hall of each bends into the basal concavity from the 

 middle part and upward at the superior end. In the azygous 

 area and in one of the other areas, it is followed by a single 

 plate, in the .second range, about one fourth as lai'ge, and it is 

 followed, in the third range by a smaller iilalv tliat unites 

 with the plates of the vault. In the other areas the second 

 interradial is smaller and is followed by two plates in the third 

 i-ange and these are followed by a single ])late in the fourth 

 range that unites witli the plates of the vault. Tlw ]ilati's in 

 the interradial areas thus vary from throe to five. 



The vault is only moderately convex, dejiressed in the inter- 

 ambulacral areas, and covered with large tubercular plat(\s. 

 The sutui'es between the plates are not shown, in tlie illusi ra- 

 tions, because only part of them can be distinguished, in our 

 specimen. The ])robo.scis or short tube for the azygous (U'itice 

 is excentric, from the azygous side, wliicli is a peculiarity not 

 often observed among the crinoids. Tiiere is a large central 



