270 PROCEEDINGS OF THE ACADEMY OP [1881. 



We arrange the six sections as follows : — 



a, Stelidiocrinites. 



1. Briarocriiius Angelin. 4. Macrostylocrinus Hall. 



2. Stelidiocrinus Angelin. Subgenus Centrocrinus 



3. Patelliocrinus Angelin. Wachsmuth & Springer. 



b. Agaricocrinites. 



5. Carpocrim/s Miiller. 6. Agnricocrinus Troost. 



Subgenus Desmidocrinus Subgenus Alloprosallocrinus 



Angelin. Lyon & Casseday. 



c. Melocrikites. 



7. Mariacrinus Wachsm. & Spr. 10. Scypliocrimis Zenker. 



8. Teehnocrinus Hall. 11. Dolatocrinus Lyon. 



9. Melocrinus Goldfuss. Subgenus Stereocrinus Barris. 



d. Perxechocrinites. 

 13. Periechocrinus Austin. 14. Megistocrinus Owen & Shumard. 



13. Abacoc7'inus Angelin. 



e. ACTINOCRINITES. 



15. Actinocrinus Miller. 19. PJiysetocrinus Meek & Worthen. 



16. Teleiocrimis Wachsm, & Spr. 20. Strotocrinus Meek & Worthen. 



17. Steganocrinus Meek & Worthen. 21. GenncBocrinus Wachsm. & Spr. 



18. Amphoracrinus Austin, 



/. BatocRinites. 



22. Batocrinus Casseday. 24. Dorycrinus F. Roemer. 



23. Eretmocrinus Lyon & Casseday. 



a. STEMDlOCRliJITES. 

 i. BRIAKOCRINTJS Angelin. 



1878. Angelin. Iconog. Crin. Suec, p. 1. 



1879. Zittel. Handb. der Palseont., i, p. 367. 



Briarocrinus represents the simplest conceivable form that can 

 be admitted among the Actinoerinidoe. It has two interradial 

 plates, and these, in the typical species, are situated above the 

 line of the third primary radials. Its perfectly straight arm 

 joints suggest an immature crinoidal structure. 



B. angustus Angl. is too plainly distinct from B. injiatus Angl., 

 in the construction of the plates of the calyx, and particularly in 

 the interradial portions, to be admitted into the same genus, and 

 as it agrees with no other, we should propose it as the type of a 



