Klem — Revision of the Palaeozoic Palae'echinoidea. 47 



contract and taper gradually toward the summit. Surface of 

 the lower portion smooth ; the upper part muricated, having 

 small spinif orm tubercles in quincunx order. Point of attach- 

 ment somewhat elongate. Annulation strongly striated. 



Geological formation and locality : Burlington Limestone, 

 Burlington, Iowa; Hannibal, Mo.; Upper Coal Measures, 

 Topeka, Kas. 



3. Archaeocidaris biangulatus Shumard. 



1858. Archaeocidaris hiangulatus. Shumard, Trans. St. 



Louis Acad. Sci., vol. 1, p. 224. 

 1874. Archaeocidaris biangidata. Loven, Kongl. Svens. 



Vetens. Akad. Handl., bd. 11, no. 7, p. 44. 

 1889. Archaeocidaris biangulata. Miller, N. Amer. Geol. 



Pal. p., 225. 



1894. Archaeocidaris biangulata. Keyes, Mo. Geol. Surv., 

 vol. 4, p. 130, pi. 15, figs. 1 a-c. 



1895. Archaeocidaris biangulata, Keyes, Proc. Iowa 

 Acad. Sci., vol. 2, p. 185, pi. 15, figs. 1 a-c. 



Areola subhexagonal, covered with very minute radiating 

 striae, inner ring narrow and prominent. 



Primary spines very long and slender, marked with fine 

 longitudinal striae. Immediately above the base the spines 

 are cylindrical, but soon become flattened and angular. The 

 edges are ornamented with short flattened projections, set 

 obliquely to the main axis. The expanded part of the base 

 of the spines is strongly striated. 



Geological formation and locality : Middle and Upper Coal 

 Measures, Lexington and Kansas City, Mo. 



4. Archaeocidaris cratis White. 



1876. Archaeocidaris cratis. White, Powell's Rep. Geol. 



Uinta Mts., p. 109. 

 1880. Archaeocidaris cratis. White, Cont. to Inv. Pal., 



No. 6, p. 130, pi. 33, fig. 2 a. 

 1889. Archaeocidaris cratis. Miller N. Amer. Geol. Pal., 



p. 225. 



