58 Trans. Acad. Sci. of St. Louis. 



Geological formation and locality : Upper Coal Measures, 

 New Mexico, San Juan region, Needle Mountains quadrangle. 



22. Archaeocidaris triserialis M'Coy. 



1844. Echinocrinus triserialis. M'Coy, Foss. of Ireland, 



p. 173, pi. 26, fig. 1. 

 1850. Echinocrinus triserialis. D'Orbigny, Prodrome, vol. 



1, p. ]54. 

 1858. Archaeocidaris triserialis. Desor, Syn., p. 155. 

 1862. Archaeocidaris triserialis. Dujardin et Hupe, Echi- 



nodermes, p. 466. 

 1874. Archaeocidaris triserialis. Loven, Kongl. Svens. 



Vetens. Akad. Handl., Bd. 11, no. 7, p. 43. 

 Spines large ornamented with three angular ridges. Each 

 ridge is ornamented with tooth-like spines. Space interven- 

 ing smooth. 



Geological formation and locality: Subcarboniferous, 

 Ireland. 



23. Archaeocidaris triserratus Meek. 



1872. Archaeocidaris ? triserrata. Meek, U. S. Geol. Surv. 



Neb., p. 151, pi. 1, figs. 6 a — c. 

 1889. Archaeocidaris triserrata. Miller, N. Amer. Geol. 



& Pal., p. 225. 

 1895. Archaeocidaris triserrata. Keyes, Proc. Iowa Acad. 

 Sci., vol. 2, p. 190. 



Primary spines slender, a little arched near the base. 

 Spines cylindrical near the base but compressed rhombic fur- 

 ther up. Margins sharp and serrated. On the middle 

 concave side of the curvature of the spine there is a third 

 serrated row, extending from the base about two-thirds of 

 the way. On the other side three or four rows of smaller 

 granules run from the base to about the middle. Ring at 

 the base faintly milled. Articulating extremity contracting 

 abruptly and finely striated. 



Geological formation and locality : Upper Coal Measures, 

 Omaha, Nebraska City, and three miles above the mouth of 



