1888.] NATURAL SCIENCES OF PHILADELPHIA. 363 



Pig. 13. Oral plates of Amphoracrinus quadrispinus. 



Pig. 14. Inner floor of the orals of a Plsocrinus from Indiana. 



Pig. 15. Vault of a young Platycrmus symmetricus W. and Sp., with 

 almost uniform orals. 

 (All specimens in the collection of Wachsmuth and Springer) 



