RHODOCRINID&. 261 
Remarks. — Rhaphanocrinus sculptus was described as monocyclic, and 
referred by S. A. Miller to Glyptocrinus. The infrabasals are only seen 
as small dots around the column. The species is readily distinguished from 
allied forms by having knife-like ridges upon the fixed brachials; while the 
back of the free brachials is perfectly round. 
LYRIOCRINUS Hatt. 
1852. Hatt; Geol. Rep. N. Y, Paleontology, Vol. IL., p. 197. 
1857. Prcrer ; Traité de Paléont., Vol. IV., p. 329. 
1862. Dusarpin and Hues; Hist. Natur. des Zooph. Echinod., p. 149. 
1866. Suumarp; Trans. Acad. Sci. St. Louis, Vol. II., p. 379. 
1867. Haut; 20th Rep. N. Y. State Cab. Nat. Hist., p. 325. 
1879. Hai; 28th Rep. N. Y. State Mus. Nat. Hist. (ed. 2), p. 189. 
1881. W. and Sp.; Revision Paleocr., Part IL., p. 203 (Proceed. Acad. Nat. Sci. Phila., p. 377). 
1881. Hazr; llth Ann. Rep. Indiana by Collet, p. 269. 
1889. S. A. Minter; North Amer. Geol. and Paleont., p. 258. 
Syn. Marsupiocrinus (not Phillips) Haut ; 1843, Geol. 4th Distr. New York, p. 114. 
Syn. Rhodocrinus (not Miller) Hatt, 1863; Trans. Albany Inst., p. 198. 
Calyx depressed-globose, more or less flattened to the middle of the 
radials; symmetry almost perfectly pentamerous; plates heavy, their surfaces 
smooth or finely granular; ventral disk not rising above the dorsal cup; arm 
openings directed upwards, placed at the upper margin of the disk. Infra- 
basals five, very small, abruptly and deeply depressed and concealed by the 
column. Basals five, of uniform size, either all hexagonal and supporting 
upon the truncate upper face the first interradial plate; or quite frequently 
one or more of them hexagonal, and angular at the top. Costals two; large. 
Two of the distichals enclosed in the calyx. Arms two to the ray, rising in 
a straight line with the sides of the calyx; simple, strong, biserial, two of the 
interlocking plates frequently in the calyx. Interbrachials four, in three 
rows: 1, 2, 1. Anal side generally not distinct, but exceptionally it has 
a special anal plate in the second row. Disk flat, somewhat depressed in the 
interradial regions ; composed of a great number of slightly convex, delicate 
pieces, and well defined orals. Anus subcentral, probably at the end of a 
small tube. 
Column of less than medium size, round; axial canal small. 
Distribution. — Upper Silurian. America and Europe. 
Type of the genus: Lyricerinus dactylus Hall. 
Remarks. — The name Lyriocrinus was proposed for a species from the 
Niagara group of Lockport, which had been described under Marsupiocrmus, 
