270 ROBERT TRACY JACKSON ON ECHINI. 



p. 191; Beede, 1900, p. 47, Plate 8, fig. 10; (?) Girty, 1903, p. 330; Klem, 1904, p. 59; Lambert and 

 Thiery, 1910, p. 125. 

 Archaeocidaris trudifera Miller, 1889, p. 225. 



Known only fragmentarily. Interambulacral plates hexagonal, height and width about 

 equal. Details of basal terrace, scrobicule, and secondary tubercles are not shown in the origi- 

 nal figures. Primary spines long, fusiform, up to about 120 mm. long. Surface for a short 

 distance above the milled ring apparently smooth, beyond which it is ornamented with numerous 

 minute spinules arranged around the spine in imperfectly spiral lines. 



Red Wall, Carboniferous (Coal Measures), Camp Apache, Navajo County, Arizona, cotypes 

 in United States National Museum 8,471. Confluence of the Grand and Green Rivers, Utah; 

 Topeka, Kansas; Leadville district, Colorado. Upper Coal Measures, Topeka Limestone, 

 Topeka, Kansas (Beede) . 



*Archaeocidaris norwoodi Hall. 



Plate 14, figs. la-Id. 



Archaeocidaris norwoodi Hall, 1858, p. 701, Plate 26, figs. 5a-5e; Keyes, 1894, p. 129; 1895, p. 188; Klem, 



1904, p. 54. 

 Cidarotropus norwoodi Lambert and Thiery, 1910, p. 125. 



Known only from dissociated plates and spines. Interambulacral plates are hexagonal, 

 or pentagonal in adradial columns, wider than high, basal terrace marked. Scrobicular area 

 sometimes shows obscure radiating plications, secondary tubercles in a narrow row on the margin 

 of the plates. Primary spines are slender, elongate, slightly curving, longitudinally striate 

 below and muricate above, with fine sharply elevated denticles, and at intervals marked by 

 larger thorn-like diverging spinules; intermediate surface cancellate or granulose. 



Kaskaskia Group, Lower Carboniferous, Chester, Illinois, American Museum of Natural 

 History; Kaskaskia, Illinois; near St. Louis, Missouri (Klem). 



Archaeocidaris paradoxa (Eichwald). 



Plate 14, fig. 2. 



Palaeoechinvs paradoxus Eichwald, 1856, p. 127; 1860, p. 650, Plate 32, fig. 25 (but not fig. 26). 

 Palaechinus paradoxus Stuckenberg, 1898, pp. 230, 343; Klem, 1904, p. 35; (?) Lambert and Thiery, 

 1910, p. 119. 



The spine, which is the only recognizable part of Eichwald's figures or description, evidently 

 belongs to an Archaeocidaris. The shaft only is known, which is stout, tapering gradually, 

 with frequent irregularly placed, stout, thorn-like spinules directed distally. What Eichwald 

 figured as a test (his Plate 32, fig. 26) is an unrecognizable mass, but is entirely the wrong shape 

 for an Archaeocidaris. It evidently has no relation to the spine. 



Upper Carboniferous (Coal Measures), Sterlitamak and Saraninsk, Ural, Russia. 



