KEVISION OF PALEOZOIC STELLEKOIDEA. 123 



the rays, and separated from the side series by intervening smaller 

 plates. Each bore several small spines, as shown by the small pits 

 for their articulation. * * * 



"The adambulacral plates are hexagonal and much wider than 

 long. They are more numerous than the marginal plates near the 

 disk, but toward the apices of the rays they interlock alternately 

 with the marginal plates. The number on each side of a furrow hi 

 a complete ray would be 50 or more. The pits for the articulation 

 of the spines are as numerous as they are on the marginal plates. 

 These two series on the ventral side of the species, with numerous 

 spines upon each plate, are in striking contrast with the plates on 

 the dorsal side of the rays, where no plate bears more than a single 

 spine. 



"The ambulacral plates have their greatest length across the 

 rays, and seem to be about as numerous as the adambulacral ones. 

 An angular depression marks the center of each ambulacral furrow, 

 upon each side of which a sharp ridge arises upon each ambulacral 

 plate, and curving forward and outward abuts against an adambula- 

 cral plate. " 



Emended description. The largest specimen, the holotype, meas- 

 ures R = (about) 67 mm., r = 17 mm., R = nearly 4r. Another speci- 

 men: 11 = 58 mm., 3* =15 mm., R= nearly 4r. 



Abactinal surface very ornamental. Medially along each ray there 

 is a radial column of highly convex plates, and two columns of similar 

 plates, the supramarginals, are situated near the margin. Between 

 the inframarginal, supramarginal, and radial columns are very nu- 

 merous diagonal rows of smaller conical or angular plates, from 2 at 

 the apex of the ray to 14 at base of same in each row on each side of 

 the radial column. This may be stated in another way. Between 

 the radial and supramarginal columns and again in the ambital area, 

 or between the supramarginals and inframarginals, the diagonal rows 

 have from one to seven plates in each area. These rows are directed 

 diagonally and distally across the rays from the sides to the median 

 column, the apex of the angle thus formed being occupied by the 

 larger plates of the radial column. All of these smaller plates appar- 

 ently bore a single short spine. Between all of the diagonal rows 

 are inserted both proximally and distally numerous minute, conical, 

 irregular-shaped plates. The supramarginal columns continue across 

 the disk and those of adjoining rays unite in the axillary areas. The 

 radial columns also extend over the disk but do not attain the center, 

 and the diagonal arrangement of the small plates ceases near the 

 proximal portion of the rays. The pattern arrangement of the disk 

 plates can not be made out since their original position is disturbed. 



Madreporite quite large, quadri-lobate in outline, depressed, convex 

 and very finely radiately striate. It is situated in one of the axillary 



