Elem — Revision of the Palaeozoic Palae'echinoidea. 27 



2. Lepidesthes laevis Trautschold. 



1879. Lepidesthes laevis. Trautschold, Mem. Soc. Imp. 

 Nat. Moscow, t. 14, p. 8. 

 Geological formation and locality: Subcarboniferous, 

 Mjatschkowa, Russia. 



III. Melonitidae Zittel, 1879.* 



Syn. Palaechinidae M'Coy 1849.t 



Melonechinidae Lambert 1900. J 



Test spherical with never less than five columns of plates 

 in each interambulacrum. Surface of the whole body cov- 

 vered evenly with fine short spines. 



a. Rhoechinus Keeping 1876. § 



From five to nine columns of plates in each interambu- 

 lacrum and two columns in each ambulacrum. Two pores in 

 each ambulacral plate. 



1. Rhoechinus burlingtonensis Meek and Worthen. 



1860. Palaechinus Burlingtonensis. Meek and Worthen, 



Proc. Acad. Nat. Sci. Phil., p. 396. 

 1866. Palaechinus burlingtonensis. Meek and Worthen 



Geol. Surv. 111., vol. 2, p. 230, pi. 16, figs. 3a-c. 

 1874. Palaechinus burlingtonensis. Loven, Kongl. Svens. 



Vetens. Akad. Handl., Bd. 11, no. 7, p. 41. 

 1889, Palaechinus burlingtonensis. Miller, N. Amer. Geol. 



Pal., p. 266, fig. 382. 

 1895. Palaechinus burlingtonensis. Keyes, Proc. Iowa 



Acad. Sci., vol. 2, p. 180. 



* Handbuch der Palaeontologie, bd. 1, p. 484. 

 t Ann. Mag. Nat. Hist., ser. 2, vol. 3, p. 251. 

 X Bull. Soc. Sci. Hist. Nat. L'Yonne, vol. 53, p. 53. 

 § Quart. Journ. Geol. Soc. Lond., vol. 32, p. 37. 



