16 Trans. Acad. Sci. of St. Louis. 



Plates imbricate more or less, the inter ambulacral aborally, 

 the ambulacral adorally. Mouth and anus opposite, the anus 

 within the apical disk. Apical system consists of ^ve genital 

 plates, each pierced by from two to five pores, and ^ve ocular 

 plates, which are sometimes pierced by two pores. 



I. Lepidocentridae Loven 1874.* 



Interambulacral plates imbricate aborally and outward. 

 Adambulacral plates larger and bearing more and larger 

 tubercles. More than two columns of plates in the interam- 

 bulacrum. Ambulacral pore pairs usually in a single series. 



a. Lepidocentrus Miiller 1856.t 



Usually five columns in the interambulacrum. Edges of 

 the middle row beveled, side columns rather four than six 

 sided. Adambulacral plates large with rounded edges. Am- 

 bulacral plates small, two columns of low six-sided inflexible 

 plates. Two pores to each plates in vertical rows. Spines very 

 small and pointed. Tubercles small and far apart. Masti- 

 catory apparatus present. 



1. Lepidocentrus eifelianus Miiller. 



1856. Lepidocentrus eifelianus. Miiller, Abhandl. K. Akad. 



Wiss. Berlin, p. 258, pi. 3, figs. 1-8. 

 1858. Lepidocentrus eifelianus. Miiller, Monatsber. K. 



Preuss. Akad. Wiss., p. 197. 

 1866. Lepidocentrus Eifelianus. Schultze, Denkschrift K. 



Akad. Wiss., Wien, Math. -Natur wiss. CI., No. 26, p. 



123, tab. 13, fig. 2. 

 1871. Lepidocentrus eifelianus. Kayser, Zeitsch. deut. geol. 



Gesell. Bd. 33, p. 340, 371. 

 1874. Lepidocentrus eifelianus . Loven, Kongl.Svens.Vetens. 



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



* Kongl. Svens. Vetens. Akad. Handl. Bd. 11, no. 7, p. 39, 

 t Abhandl. K. Akad. Wiss. Berlin, 1866, p. 258. 



