NIAGARA GROUP. 
197 
Genus LYRIOCEINUS ( nov. gen.). 
[ Gr. Xupiov, lyra parva, and xpivov, lilium .] 
Column round ; pelvie plates five, pentagonal; costal plates five, restlrg on the oblique 
upper edges of the pelvic plates, and succeeded by five scapulars, which support an arm- 
plate, upon the oblique upper edges of which rest the hand-joints supporting a pair of 
fingers; a single interscapular plate between each pair of scapulars, with the two second 
interscapular plates resting upon its oblique upper edges and the edges of the adjoining 
costal plates. 
The arrangement of the plates in this genus commences upon the simplest plan known^ 
that of the continuation of the plates in the second series in a direct line to the base of 
the arms. The number of plates interposed, however, between the pelvis and the sub¬ 
divisions at the base of the arms, shows a higher type, which is further indicated in the 
arms, the fingers of which are composed of a double series of plates. 
589. 1. LYRIOCRINUS DACTYLUS. 
Pl.XLIV. Fig. 1 « - g. 
Marsupiocrinites? dactylus. Hall, Geol. Rep. 4tli Dist. N. York, pag. 114,•'"fig. 4, p. 113, 1843. 
Column round, composed near the head of alternating larger and smaller joints, the 
larger projecting much beyond the smaller ones; canal apparently round; surface of 
plates finely ornamented; pelvic plates small, pentagonal; costal plates heptagonal, 
scapulars hexagonal (in one of the five there is a double scapular, and the succeeding 
plate is somewhat smaller than in the others); arm-plates of the form of the pelvic plates; 
hand-joints two, one above the other, the lower somewhat cuneate, resting on each of the 
sloping upper sides of the arm-plate ; fingers ten, composed of a double series of joints 
interlocking with each other, gradually tapering to the extremity. The intermediate 
plates are uniform, with one exception : a quadrangular plate is interposed between 
the two seeond interscapular plates; this point is on the opposite side from the super¬ 
numerary scapular, and both may be seen in fig. 1 d. Between each pair of fingers there 
are two small plates interposed at the base, directly above the interscapulars; and 
between the fingers of the same pair there is a single pentagonal plate interposed, similar 
to the larger of the two plates between the pairs of fingers. 
This species is readily distinguished by the great number of plates below the sub¬ 
divisions of the arms, which take place in a direct line from the divisions between the 
