IOWA ACADEMY OP SCIENCES. 
189 
Archceocidaris gracilis Newberry, 1861; Kept. Colorado Riv. 
West, Ives’ Exp., p. 117, pi. i, figs. 4-4a. 
ArchcBOcidaris edgarensis Worthen & Miller, 1883; Geol. Sur. 
Illinois, vol. VII, p. 337, pi. xxx, figs. 15«-c. 
Archceocidaris acideata ~Kejes, 1894; Missouri Geol. Sur., vol. IV, 
p. 130, pi. XV, fig. 3. 
Known only from spines, which are long, with numerous 
short spinous processes, lower part contracted somewhat. 
Horizon and loccdities. Upper Carboniferous, Upper Coal 
Measures: Nev/ Point (Jackson county), Missouri. 
ARCHmociDARis BIANGULATA Shumard. 
Archceocidaris Ijiangulcda Shumard, 1858; Trans. St. Louis Acad. 
Sci., vol. I, p. 224. 
Archceocidaris hiangidcda Keyes, 1894; Missouri Geol. Sur., vol. 
IV, p. 130, pi. XV, figs. la-c. 
Interambulacral plates as in A. agassizi, but somewhat wider 
than high, and with the boss much larger. Spines moderately 
stout, with a broad alate extension running longitudinally on 
opposite sides from near the crenulated annulation to the end. 
Both the central thickened portion of the spine and its expan- 
sions are covered by small scattered spinous tubercles. 
Horizon and loccdities. Upper Carboniferous, Upper Coal 
Measures: Lexington and Kansas City, Missouri. 
ARCHmociDARis MEGASTYLUS Shumard. 
Archceocidaris megastylus Shumard, 1858; Trans. St. Louis Acad. 
Sci., vol. I, p. 225. 
Archceocidaris megastylus Keyes, 1894; Missouri Geol. Sur., vol. 
IV, p. 129, pi. XV, figs. 2a-b. 
Known only from loose spines and plates. Interambulacral 
plates very large and heavy, hexagonal, margins slightly 
turned upward; central tubercle large, considerably elevated; 
marginal nodes rather small, distant. Surface smooth. Spines 
large, attaining a length of eight or nine centimeters; very 
heavy, and nearly of a uniform size throughout the entire 
length. A few long spinous projections stud the surface at 
irregular distances. 
Horizon anct localities. Upper Carboniferous, Upper Coal 
Measures: Independence (Jackson county), Missouri. 
