INVERTEBRATES, 147 



RADIATA. 

 ECHINODERMATA. 



CRINOIDEA. 

 Genus ACTINOCRINUS, Miller. 



Synon. — Aclinocrinites, Miller, 1821. Nat. His. Crinoidea. 



Aclinocrinus, Agassiz, 1835. Mem. Soc. Sci. Neuchat., 1. 



Welocrinites, (sp.), Goldp., 1839. Act. Nat. Curios., XIX; (not 1826 Petref. 



Germ. 1, p. 197.) 

 Melocrinus, (sp.), Bronn, 1848. Nom. Palseont. 1, p. 719; (not Ag. 1835.) 

 Abracrinus, d'Orbiqny, 1850. Palseont. Stratigr. 1, p. 156. 

 Conocrinus, Troost, 1850. List Crin. Tenn. Proc. Am. Ass., Cambridge, p. 60. 

 Batocrinus, Casseday, 1854. Zeitschr. Deutsch. Geol. Gessellsch, VI, p. 237. 

 Eretmocrinus, Lyon and Casseday, 1859. Am. Jour. Sci., (2), Vol. XXVIII, 



p. 241. 

 Alloprosallocrinus, Lyon and Casseday, 1860. Am. Acad. Arts and Sci., Vol. 



V, p. 29. 

 Uperocrinus, Meek and "Worthen, Aug., 1865. Pro. Ac.Nat. Sci.,Philad., p. 153. 

 * Generic Formula. — 



Basal pieces, 3. 



Subradials, 0. 



Radials, 3 -f- 5. 



Secondary do., to 1 or 2 -f- 10. (Sometimes 1 in 3 rays, and 2 in each of 



the others. 

 Interradials, 1 to 13, or more. 



Anal pieces, 3 to 15, or more; the first one resting on the base. 

 Opening of summit, sub-central or central — with or without a proboscis. 

 Arms, 12 to 30, or more. 

 Column, round, with a cylindrical or more or less pentagonal cavity. 



Body, when divested of the arms and column, presenting 

 every diversity of form, from sub-globose to fusiform, conic, 

 sub-discoid, wheel-shaped, pyriform, etc. The three basal pieces 

 are arranged so as to form a flattened hexagonal disc, or a 

 more or less elevated cup. Of the five first radial pieces, three 



* It is very probable that at least a part of the characters generally expressed in 

 what are now called the generic formulas of Crinoids, will be found to be rather family 

 characters than generic. 



