it THE CRINOIDEA CAMERATA OF NORTH AMERICA, 
at the distal end, where they form a large root with hundreds of small, very 
delicate branchlets. 
In Dichoerinus the distribution and length of the cirri are extremely vari- 
able. In some species they only occur at the lower part of the stem, where 
they are short and arranged far apart. In others they continue up to near 
the calyx, and are quite long. The former is the case in D. inornatus, in 
which they are singly arranged, and rather slender. In D. parvulus and 
D. delicatus, however, they follow the whole length of the stem, and are 
arranged in sets of two or more, which are so long that the tips of the upper 
ones reach up to the arms. But the most remarkable cirri occur in the 
Carboniferous Camptocrinus myelodactylus (Plate LXXYV. Figs. 1 and 2) and 
C. cirrifer (Plate LX XVI. Figs. 13 a, 4, ¢), in which they begin at a short 
distance from the calyx. The stem, as usually found in these species, is 
coiled around the crown; the joints are circular at the top, but gradually 
become crescent-shaped, the concave side of the crescent directed to the 
inner side of the coil, and both its horns giving off extremely long cirri from 
alternate sides. Very similar cirri occur in the Fistulate genus Herpetocrinus, 
from the Silurian of Europe. 
Glyptocrinus apparently had no cirri at all, not even at the distal end, 
and the stem was probably attached like that of the Comatule in their 
larval state by means of a dorso-central, i. e., the enlarged terminal plate. 
Rhodocrinus nanus and R. Kirbyi have a few scattered cirri at the lower end, 
singly arranged. 
The cirri of the Inadunata, so far as observed, are not only more slender, 
but were apparently more flexible than those of the Camerata, and they 
pass up more frequently to the top of the stem, The latter is often the case 
among the Poteriocrinide, especially in Scaphiocrinus and Graphiocrinus, in 
which the nodal joints have variously from one to five rather delicate cirri. 
That these appendages were highly flexible is shown by the fact that they 
bend in all directions, —some being straight, others curling, some directed 
upward, others downward, —a feature very different from that shown in the 
Platycrinide, Actinocrinidx, and Batocrinide. 
Belemnocrinus florifer has very long and slender interradially disposed 
cirri, which extend to the full length of the stem. It has three or four from 
each nodal joint, the upper ones directed upwards, and extending to half the 
height of the arms. J. /ypus, on the contrary, has no cirri to a length of 
13} cm., and the stem is circular instead of stellate. 
