IIS 
PALAEONTOLOGY OF NEW-YORK. 
Genus Braciiiocrinus (n.g.). 
[ Gr. /3pa^iov, brachium; xpivo£, liliuni .] 
Body unknown or none. 
Arms composed of numerous articulations arranged in single consecutive 
series (or of pentagonal joints in double series ? ). Base of arm rounded, 
without articulating surface. Tentacula composed of thickened node¬ 
like joints. 
Brachiocriiras nodosarius (n. s.). 
Plate Y. Fig. 5 - 7; and Plate YI. Fig. 1-3. 
Body unknown. 
Arms very long, composed of numerous articulations arranged in single 
series, very convex exteriorly and flattened or slightly concave on the 
inner side, very gradually diminishing from the base. Articulations 
nearly three times as wide as long : from every fourth or fifth, and 
sometimes from each third joint, originates a tentacle on one side, and 
one from the next succeeding joint on the opposite, giving them the 
appearance of being opposite and in pairs. Tentacula composed of 
thick bead-like joints, which increase in size from the base to the 
middle, and thence diminish to the extremities. Section of tentacula 
round, with a linear foramen, and without any appearance of a groove 
or canal on the inner side. 
Although I have seen no part of a body which could be regarded as belonging 
to this crinoid, the character of the arms is so peculiar, that I am induced to de¬ 
signate the genus from the feature presented in these appendages. The arms are 
sometimes much elongated, as seen in the specimen, Plate v, fig. 2, which is nearly 
four inches in length and still far from being entire. There is often much irregularity 
in the distance from each other of the tentacula : in several specimens, they originate 
at every fifth or sixth plate of the arm; while in one individual, the greater number 
originate on every third or fourth plate; and in one or two instances, there is only 
a single intervening plate. I have also noticed that upon the inner side of the arm, 
the two adjoining plates bearing tentacles on the opposite edges are sometimes 
anchylosed, presenting the appearance of a single thick plate. 
