48 Trans. Acad. ScL of St. Louis. 



1895. Archaeocidaris cratis. Keyes, Proc. Iowa Acad. Sci., 



vol. 2, p. 188. 

 1903. Archaeocidaris cratis. Girty, U. S. Geol. Surv., 

 Professional Paper No. 16, p. 331. 



Spines slender, tapering gradually to the apex, ornamented 

 with well defined spinules some distance apart. Basal ring 

 prominent with finely crenulated edges, otherwise plain. 



Geological formation and locality: Middle Carboniferous, 

 confluence of the Grand and Green Eivers, Utah ; Crested 

 Butte district, Leadville district* and Ouray, Colo. 



5. Archaeocidaris dininni White. 



1880. Archaeocidaris dininni. White, Proc. U. S. Nat. 



Mus., vol. 2, p. 260, pi. 1, figs. 13-15. 

 1880. Archaeocidaris dininni. White, Cont. to Inv. Pal., 



No. 6, p. 131, pi. 35, figs. 6 a^c. 

 1889. Archaeocidaris dininni. Miller, N. Amer. Geol. Pal., 



p. 225. 



1894. Archaeocidaris dininni. Keyes, Mo. Geol. Surv., 

 vol. 4, p. 130, pi. 15, figs. 6 a-c. 



1895. Archaeocidaris dininni. Keyes, Proc. Iowa Acad. Sci., 

 vol. 2, p. 190, pi. 18, figs. 6 a-c. 



Primary spines fusiform and strong. Neck short and plain, 

 the rest of the spine studded with many spinules at nearly 

 right angles to the main axis, except near the summit where 

 they stand obliquely upward. Spinules most numerous and 

 strongest near the base. Smaller spines more slender and 

 some without a basal ring. 



Geological formation and locality: Upper Coal Measures, 

 near Tecumseh, Neb. ; Kansas City, Mo. ; Red Oak, Iowa. 



6. Archaeocidaris edgarensis Worthen and Miller. 



1883. Archaeocidaris edgarensis. Worthen and Miller, 

 Geol. Surv. 111., vol. 7, p. 337, pi. 30, figs. 15 Sr-c. 



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

 Pal., p. 225. 



