30 Trans. Acad. Sci. of St. Louis. 



4. Rhoechinus irregularis Keeping. 



1876. Rhoechinus irregularis. Keeping, Quart. Journ. GeoJ. 

 Soc. Lond., vol. 32, pt. 1, p. 37, pi. 3, figs. 6-8. 



Small and depressed at poles. Interauibulacra composed 

 of plates which are covered with minute sharp granules. 

 Ambulacral areas sunk and narrow. The plates are trans- 

 versely elongate with the pores in the center. One inter- 

 ambulacral plate is equal to four or five ambulacral plates. 

 Both interambulacral and ambulacral plates imbricate. 



Geological formation and locality: Carboniferous, Hook 

 Head, Wexford Co., England. 



5. Rhoechinus quadriserialis Wright. 



1865. Palaechinus quadriserialis. Wright, Dub. Quart. 



Journ. Sci., vol. 5, p. 260, pi. 8, fig. 1. 

 1874. Palaechinus quadriserialis. Loven, Kongl. Svens. 



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

 1889. Palaechinus quadriserialis. Duncan, Ann. Mag. Nat. 



Hist., ser. 6, vol. 3, p. 204. 

 General form elliptical. Interambulacral areas composed of 

 four columns. One adambulacral plate equals in width six or 

 seven ambulacral plates. Two rows of pores on each side of 

 the ambulacra. 



Geological formation and locality: Carboniferous, Ireland. 



UNDETERMINED SPECIES. 



1. Rhoechinus sp. Duncan. 



1889. Rhoechinus sp. Duncan Ann. Mag. Nat. Hist., ser. 6, 

 vol. 3, p. 204. 



2. Rhoechinus (?) Tornquist. 



1897. Rhoechinus (?). Tornquist, Abhdl. Geol. Special Karte 

 Elsass-Lothr., Bd. 5, heft. 6, p. 763, taf. 20, fig. 8. 



