106 
PALAEONTOLOGY OF NEW-YORK. 
row of tentacula along the fingers. Tentacula round, jointed ; articula¬ 
tions nearly twice as long as broad : each articulation, from near its 
centre on the inner side, giving origin to a secondary round jointed 
tentacle, producing in this manner a first and second series of tentacles. 
Interbrachial plates seven or eight or more below the base of the 
proboscis, on each of the four regular sides. 
Column round, consisting of joints of nearly equal thickness, becoming 
thinner towards the body. Canal small. 
This magnificent species of crinoid differs from several smaller forms of the genus 
in the smoother plates, which show some remains of obtuse radiating ridges towards 
their margins in some of the higher plates of the body; while the lower plates are 
essentially smooth, or with no ornament beyond the fine granulose surface. The 
structure of the brachial portion is remarkable in presenting an auxiliary arm on 
each side of the base of the principal arm, and which proceed from the lower bra¬ 
chial plates, and have essentially an origin independent of the central arm. 
A remarkable feature of this and other species of the genus is that the main arms 
give origin to armlets (or fingers, in the nomenclature of Miller), which bear the 
tentacula; while the joints of the main arms do not appear to bear tentacula, as far 
as can be observed. 
In all the individuals of this species which have been seen, the extremities of the 
arms are broken off, and the entire length and expansion are not known. In one 
specimen, thirty armlets can be distinctly counted on each side; and from the size 
of the arm where broken off, it is probable that five or six, or perhaps ten more, 
may have existed. 
The proboscis is only partially shown in a single specimen : its full length is 
unknown. The column in the small fragment attached to the specimen, Plate n, is 
composed of thin joints; while the fragment lying on the specimen, Plate n a, and 
other fragments of columns supposed to belong to this species, are composed of 
thicker joints. Judging both from the numerous fragments of columns found with 
this species, and from the known length of the column in another species, this 
crinoid was doubtless furnished with a long and strong column. 
PLATE II. 
Fig. 1. An individual nearly entire, showing a few joints of the column, the plates of the 
body, the arms, and appendages. 
Fig. 2. Enlargement of a portion of one of the arms and armlets. 
Fig. 3 & 4. Enlargement of a portion of one of the armlets, and of one of the first series 
of tentacula, showing the character and arrangement of the second tentacula. 
