46 Trans. Acad. Set of St, Louis. 



areola is broad with the exterior margin marked with very 

 obscure radiating striae. Around the areola is a ring of sec- 

 ondary tubercles, succeeded by many fine granules and sec- 

 ondary tubercles. 



The primary spines are elongate, fusiform, with strongly 

 curved bases. Some are also slightly curved at the apex. 

 The base ring is small and fiuely milled. Surface finely stri- 

 ated longitudinally and covered with many short spines set 

 obliquely to the main axis. 



Geological position and locality : Middle Permian, west of 

 Council Groves, Kansas; Upper Coal Measures, Verdigris 

 River Valley, and Santa Fe Road; Fort Belknap, Texas; 

 New Point, Jackson County, Missouri. 



2. Archaeocidaris agassizi Hall. 



1858. Archaeocidaris agassizi. Hall, Geol. Iowa, vol. 1, 

 pt. 2, p. 698, pi. 26, figs. 1 a^d. 



1874. Archaeocidaris Agassizi. Loven, Kongl. Svens. Vet- 

 ens. Akad. Handl., Bd. 11, No. 7, p. 43. 



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

 Pal., p. 225, fig. 249. 



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

 vol. 4, p. 127, pi. 15, fig. 5. 



1895. Archaeocidaris agassizi, Keyes, Proc. Iowa Acad. Sci., 

 vol. 2, p. 185, pi. 18, fig. 5. 



1896. Archaeocidaris agassizii. Jackson, Bull. Geol. Soc. 

 Amer., vol. 7, p. 213. 



1897. Archaeocidaris agassizi. Beede, Trans. Acad. Sci. 

 Kas., vol. 16, p. 77. 



1900. Archaeocidaris agassizi. Beede, Univ. Geol. Surv., 

 Kas., vol. 6. p. 48, pi. 8, figs, ^-'o e. 



Primary tubercle slender, tubuliform, projecting above the 

 surrounding annulation. Deep concavity between the tubercle 

 and the inner edge of the annulation. Distinct annular 

 ridge followed by a depression and a second elevation toward 

 the margin which is ornamented with nodes. 



Primary spines, elongated and compressed. Below they 



