188 
IOWA ACADEMY OF SCIENCES. 
Arch^ocidaris norwoodi Hall. 
Archceocidaris noriuoodi Hall, 1858; Geology Iowa, vol. I, p. 701, 
pi. xxvi, figs. 5a-e. 
ArchcBocidaris noriooodi Keyes, 1894; Missouri Geol. Sur., vol. 
IV, p. 129. 
Interambulacral plates with smaller tubercles than in A. 
agassizi. Spines small, slender, with sharp, scattered spinous 
processes on the upper half. 
Horizon and localities. Lower Carboniferous, Kaskaskia lime- 
stone: Chester, Illinois. 
Arch^ocidaris mucronata Meek & Worthen. 
Arclmocidaris mucronata Meek & Worthen, 1860; Proc. Acad. 
Nat. Sci., Phila., vol. XI, p. 395. 
Ardmocidaris mucronata Meek & Worthen, 1866; Geol. Sur. Illi- 
nois, vol. II, p. 295, pi. xxiii, figs. 3a-c. 
Known only from detached interambulacral plates and the 
primary spines. The ossicles are hexagonal, slightly wider 
than high, nearly smooth, with a marginal row of small gran- 
ules and a prominent central tubercle. Spines long, gradually 
tapering, giving off numerous sharp spinous processes from a 
short distance above the proximal end to the pointed top. 
Articulating end rather large and provided with a well pro- 
nounced annulation. 
Horizon and localities. Lower Carboniferous, Kaskaskia 
limestone: Liberty (Randolph county) and Chester, Illinois. 
Archceocidaris gratis White. 
Archceocidaris cratis White, 1876; Geology Uinta Mts. , p. 109. 
Archceocidaris cratis V7hite 1883; U. S. Geol. & Geog. Sur. Terr., 
12th Ann. Rep., p. 130, pi. xxxiii, fig. 2«. 
Primary spines only known, similar to A. mucronatus, but 
more slender, annulation more prominent, spinous processes 
less numerous. 
Horizon and localities. Carboniferous, Coal Measures (Lower 
Aubrey): Utah. 
ARCHmociDARis ACULEATA Shumard. 
Archceocidaris aculeata Shumard, 1858; Trans. St. Louis Acad. 
Sci., vol. I, p. 223. 
Archceocidaris verneuiliana Swallow, 1858; Trans. St. Louis Acad. 
Sci., vol. I, p. 180. (Not King: Per. Foss., pi. vi, figs. 
22-24.) 
