104 CARBONIFEROUS PERIOD. 



Class ECHINODERMATA. 



Order ECHINOIDEA. 

 Fajiily ARCH^00IDARIDJ3. 



Genus ARCH^OCIDARIS McCoy, 1S44. 

 Archaeocidaris ornatus Newberry. 

 Plate VI, fig. 7. 

 Arcliwocidaris ornahis Newberry, 1861, Geol. Rep. Lieut. Ives's Expl. Col. Riv., 116. 



Principal spines fusiform, strong, about seven centimeters long; great- 

 est diameter a little below the middle, wliere it is about five millimeters; 

 surface for a short distance above the basal ring plain or not conspicuously 

 marked; above this plain space to the distal end, it is thickly set with spin- 

 ules from one to two millimeters in length, which are aiTanged around the 

 spine in itnjDerfectly spiral lines, in which lines the intervals between the 

 spinules are generally less than the diameter of their bases, but the vertical 

 intervals are somewhat greater; basal ring rather large, crenulated at the 

 border. An imperfect interambulacral plate embedded in the rock near one 

 of the spines contained in the collection, and probably belonging to tliis 

 species, shows a plain areolar surface, a raised center, and an elevated rim 

 around a rather small central tubercle. Remainder of the body unknoAvn. 



Dr. Newberry's type-specimens were obtained from strata of the Car- 

 boniferous period near the confluence of the two Colorados, and also from 

 strata of the same period near the Great Canon of the Colorado River. ^ 



Position and locality. — Strata of the Carboniferous period; ten miles west 

 of Ojo del Oso, near Fort Wingate, Ncav Mexico. 



Archaeocidaris trudifer White. 



Plato VI, fig. 8 a and b. 



Archceocidaris trudifer White, 1874, Exp. & Surv. west 100th Merid., Prelim. 'Rep. 

 Invert. Foss., 17. 



Interambulacral plates comparatively broad, rather thin, having an 

 elevated border all around, which is apparently composed of a series of 

 small tubercles; areolar surface apparently plain; central tubercle small, 

 perforate at the center, siuTounded at its base by a very slightly -raised ring, 



