IOWA ACADEMY OF SCIENCES. 
187 
other remains found at Booneville of what appears to be the 
same form it may be inferred that it is identical with A. keokuk, 
and until more satisfactory evidence is forthcoming Miller’s 
name may be ignored altogether or regarded as a synonym of 
Hall’s. 
Arch^ocidaris wortheni Hall. 
Archceocidaris ivortheni Hall, 1858; Geology Iowa, vol. I, p. 700, 
pi. xxvi, figs. 4a-g. 
Archceocidaris toortlieni Keyes, 1894; Missouri Geol. Sur., voL 
IV, p. 128, pi. xvi, figs. 3a-&. 
Test subglobose. Interambulacral areas made up of four 
rows of large hexagonal plates; central tubercle about one-half 
as broad as the plate, with the boss moderately elevated; sur- 
face of the plates glabrate, except at the borders where the 
marginal row of nodes is quite narrow. Ambulacral area nar- 
row, about one-half as wide as the large hexagonal ossicles, 
composed of rectangular plates, which are about twice as wide 
as high, about ten occupying the height of an interambulacral 
piece, each having a pair of large oval pores. Spines rather 
small, slender, slightly curved, with an apparently smooth or 
finely granular surface, below expanding rapidly into the broad 
crenulated annulation. 
Horizon and localities. Lower Carboniferous, St. Louis lime- 
stone: St. Louis, Missouri. 
Archa:ocidaris newberryi Hambach. 
Arclimocidaris newljerriji Hambach, 1884; Trans. St. Louis Acad. 
Sci., vol. IV, p. 551, pi. D, fig. 1. 
Archceocidaris newberryi Keyes, 1894; Missouri Geol. Sur., vol. 
IV, p. 129. 
Very closely related, and perhaps identical with, A. sJiu- 
mardiana. 
Horizon and localities. Lower Carboniferous, St. Louis lime- 
stone: St. Louis, Missouri. 
Archa:ocidaris illinoisensis Worthen & Miller. 
Archceocidaris illinoisensis Worthen & Miller, 1883; Geol. Sur. 
Illinois, vol. VII, p. 338, pi. xxxi, figs. la-b. 
Spines like A. agassizi but somewhat stouter and granula- 
tions less numerous. 
Horizon and localities. Carboniferous, St. Louis limestone: 
Hardin county, Illinois. 
