ARCHAEOCIDARIS. 273 



*Archaeocidaris megastyla Shumard and Swallow. 

 Plate 14, fig. 13. 



Archaeocidaris mcgastylus Shumard and Swallow, 1858, p. 225; Keyes, 1894, p. 129, Plate 15, figs. 2a, 2b; 

 1895, p. 189, Plate 18, figs. 2a, 2b; Beede, 1900, p. 49, Plate 8, fig. 7; Klem, 1904, p. 51. 



Archaeocidaris mcgastylis Loven, 1874, p. 44. 



Cidarotropus megastylus Lambert and ThieYy, 1910, p. 125. 



Known incompletely from plates and spines. Interambulacral plates are large, hexagonal, 

 wider than high, rather thick; scrobicular area very broad, nearly circular; primary tubercle 

 very large, and relatively large secondaries are in a narrow row on margin of plates. Primary 

 spines long, robust, circular in section, length about 3 inches. In the original description 

 Shumard and Swallow say the spine is studded with rather distant granules, or minute short 

 spines. Keyes's interpretation of the species is spines with rather large spinules of which he 

 gives a good figure. As Shumard and Swallow published no figure and their specimens may have 

 been worn, I accept Keyes's version and consider the spinules as relatively large. This char- 

 acter is shown well in a specimen in the United States National Museum which I figure and which 

 in other respects appears referable to this species. 



Upper Coal Measures, near headwaters of Verdigris River, and in the Valley of Cotton- 

 wood Creek, Kansas; Independence, Jackson County, Missouri; St. Louis Group, St. Louis, 

 Missouri, United States National Museum Collection 43,009, from E. O. Ulrich Collection 

 (Plate 14, fig. 13); Kansas City (Beede). 



*Archaeocidaris biangulata Shumard and Swallow. 

 Plate 14, figs. 9a-9d. 



Archaeocidaris biangulatus Shumard and Swallow, 1858, p. 224; Klem, 1904, p. 47. 



Archaeocidaris biangulata Loven, 1874, p. 44; Keyes, 1894, p. 130, Plate 15, figs, la-lc; 1895, p. 189, 



Plate 18, figs, la-lc. 

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



Known from dissociated plates and spines. Interambulacral plates hexagonal, wider than 

 high, basal terrace marked, secondary tubercles in a narrow row on the margin of the plates. 

 Shumard and Swallow say areolar surface with radial striae ; but such are not visible in speci- 

 mens I have seen. Primary spines are very striking in character. They are smooth for a 

 slight distance above the milled ring; the shaft is terete throughout, but is ornamented with 

 two strongly marked, opposite, wing-like expansions which are in part at least nearly entire 

 in outline, or serrately spinose. Distally the flanges pass into the general spinulose character 

 of the shaft. Aside from the flanges, the shaft is nearly smooth at least proximally, but distally 

 the whole of the shaft is thickly set with relatively long, pointed spinules closely resembling 



