Klein — Revision of the Palaeozoic Palae'echinoidea. 23 



1873. Pholidocidaris irregularis. Meek and Worthen, Geol. 

 Surv. 111., vol. 5, p. 512, pi. 15, fig. 9. 



1874. Pholidocidaris irregularis. Meek, Amer. Journ. Sci., 

 ser. 3, vol. 7, p. 375. 



1874. Pholidocidaris irregularis. Loven, Kongl. Svens. 



Vetens. Akad. Handl., Bd. 11, no. 7. p. 40. 



1889. Pholidocidaris irregularis. Miller, N. Amer. Geol. 

 Pal., p. 269. 



1895. Pholidocidaris irregularis. Keyes, Proc. Iowa Acad. 

 Sci., vol. 2, p. 180. 



1896. Pholidocidaris meeki. Jackson, Bull. Geol. Soc. 

 Amer., vol. 7, p. 210, pi. 9, fig. 54. 



Interambulacral plates thin and sharp at the edges. Pri- 

 mary tubercle present on lower (?) part only and on the 

 marginal plates, in the upper (?) part. Ambulacral plates 

 very irregular, six or more columns. Pores in pits in the 

 center of each plate, surrounded by a circular depression. 

 Primary spines taper gradually, are rounded, nearly straight, 

 and marked with minute, crowded longitudinal striae. 



Geological formation and locality : Keokuk and Hamilton 

 Groups, near Nauvoo and Warsaw, 111. 



INSUFFICIENTLY DETERMINED SPECIES. 



1 . Pholidocidaris gaudryi Julien. 



1874. Lejndocentrus Miinsterianus . Julien, Compt. Rend. 

 Acad. Sci. Paris, T. 78, p. 76. 



1890. Melonites Gaudryi. Julien, Compt. Rend. Acad. Sci. 

 Paris, T. 110, p. 737. 



1896. Pholidocidaris Gaudryi. Julien, Terr. Carb. Marin 

 de la France Centrale, p. 131, pi. 6, figs. 1, 2, 6, 7. 



Geological formation and locality : Carboniferous, l'Ar- 

 doisiere. 



2. Pholidocidaris tenuis Tornquist. 



1897. Pholidocidaris tenuis. Tornquist, Abhdl. Geol. 

 Karte Elsass-Lothr., Bd. 5, Hft. 6, p. 767, taf. 21, 

 figs. 8, 9; taf. 22, fig. 8. 



