I^lem — Revision of the Palaeozoic Palae'echinoidea. 45 



IV. Archaeocidaridae M'Coj 1844.* 



Test spherical, more or less compressed or flattened. 

 Never less than four columns of plates in each interambu- 

 lacrum. Each interambulacral plate is provided with a large 

 tubercle for the attachment of a long spine. Two columns 

 of plates in each ambulacrum, each plate pierced by two 

 pores. Plates imbricate slightly. 



a. Archaeocidaris M'Coy 1844. f 



Syn. Echinocrinus Agassiz 1841. J 



Palaeocidaris Desor 1846. § 



Each primary tubercle is surrounded by a flat scrobicule 

 and a circlet of granules. 



&■ 



1. Archaeocidaris aculeatus Shumard. 



1858. Archaeocidaris verrieuiliana. Swallow. Trans. St. 

 Louis Acad. Sci., vol. 1, 180. 



1858. Archaeocidaris aculeatus. Shumard, Trans. St. Louis 

 Acad. Sci., vol. 1, p. 223. 



1874. Archaeocidaris aculeatus. Loven, Kongl. Sveus. Vet- 

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



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

 p. 225. 



1894. Archaeocidaris aculeata. Keyes, Mo. Geol. Surv., vol. 

 4, p. 130, pi. 15, flg. 3. 



1895. Archaeocidaris aculeata. Keyes, Proc. Iowa Acad. 

 Sci. vol. 2, p. 188, pi. 18, fig. 3. 



The primary tubercles are small but prominent, situated 

 on an elevated smooth boss with deep circular canal. The 



* Foss. of Ireland, p. 173. 



t Fo88 of Ireland, p. 173. 



% Monographies des Echiuodcrmes 2de liv., p. 15. 



§ Catalogue raisson^, p. 36. 



