16 THE CRINOIDEA CAMEEATA OF NOETH AMEEICA. 



Jr.,^ who made the Crinoidea in the widest sense a class of the Echinoder- 

 mata, to which they gave the name "Pinnastella." Among the hatter thej 

 placed as orders : — 



I. CIONA CINETI (Stalked Crinoids). II. LIBERIA (Free-floaters). 



Families : Apiocrinoidea. Guathocrinoidea. 



Poteriocrinoidea. Astracrinoidea. 



Encrinoidea. Comastella. 



Pentacrinoidea. 

 Marsiipiocrinoidea. 

 Platycrinoidea. 

 Actinocrinoidea. 

 Dimerocrinoidea. 



Only the Platycrinoidea and Poteriocrinoidea t were defined. 



To the former they referred the genera : Platycrinus, Dichocrinus, Hexa- 

 crinus, Caryocriniis, and Cyathocrinus ; to the latter : Poteriocriniis, SymhatJio- 

 criniis, Extracrimis, and Pentacrinus. Their Encrinoidea include : Pncrinites, 

 Eiicalyptocrinites, Ciipressocrinites, and Euryocrinites ; their Marsupiocrinoidea : 

 Marsupiocrinites and Crotalocrinites ; the Actinocrinoidea : Actinocrinites, Rho- 

 docriniteSy Melocrinites and Tetracrinites. The Austins placed the Blastoidea 

 with the Sphaeroidocrinoidea^ and the Periechinidse under the Columnida. 



D'Orbigny in 1852 1 undertook to subdivide the Crinoids (including 

 Blastoids and Cystids) into twelve families, which contain most heterogene- 

 ous elements. For description he divided the plates of the calyx into 

 zones, without reference to their radial or interradial position. 



The next classification was that of Ferd. Koemer, who wrote in 1855, § 

 and divided the Crinoidea into three great groups : — 



I. Actinoidea, or true Crinoids, having large, pinnule-bearing arms. 



II. Cystidea, Crinoids in which the arms are feebly developed or wanting, and mouth 

 and anus are separate. 



III. Blastoidea, Crinoids without arms, the soft parts of the animal enclosed within a 

 calyx, which is closed from all sides, leaving only a few openings. 



The Actinoidea embrace : 

 A. The Astylida, Actinoidea, Crinoids without jointed column. 



a. Attached by the lower face of the calyx. 



Holopocrinidse and Cyathidiocrinidse. 



b. Calyx free. 



Astylocrinidee, Marsupitidae, Saccocomidse, and Comatulidse. 



* Ann. and Mag. Nat. Hist., first series, Vol. X., pp. 108 to 109. 



f Recent and Fossil Crinoids. Thos. Austin and Thomas Austin, Jr , London, 1843. 



J Cours elementaire de Paleontologie, II, 



§ Lethaea geognostica (Ausgabe III.), 1855, pp. 210-285. 



