48 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
by Wachsmuth and Springer, and goes far to prove that the stem must 
originally have had a far more intimate connection with the calyx than its 
representatives of to-day have ; and the fact that in a number of Paleozoic 
Crinoids the axial canal is very wide, compared with that of recent types, 
seems to indicate an additional function to that of the axial canal, which, as 
Neumayr suggests, we cannot explain from recent representatives.” 
The apposed faces of the stem joints, with a few exceptions, are marked 
by a series of more or less well defined angular ridges and alternating fur- 
rows, which radiate from the opening of the central canal toward the dorsal 
margin of the joints, but occasionally are restricted to their marginal por- 
tions. The principal ridges alternate with smaller ones, which do not extend 
as far inward as the others, and all ridges of one joint meet corresponding 
furrows of the apposed joint, which gives to the suture its serrated outline. 
The faces of the joints are flat, or slightly curved, the nodal ones having 
sometimes a slight crest around the canal, which fits into a corresponding 
depression of the apposed internodal. This indicates that the motion of the 
stem was quite limited, and, as Carpenter remarks, “only of a passive char- 
acter, due to the current of the water, etc., and independent of the will of 
the animal.” On coming in contact with other animals it was capable of 
bending sideways, and of returning to its natural position when the obstruc- 
tion was removed. 
In Platycrinus and Bourgueticrinus, in which the faces of the stem joints 
are elliptic, their surfaces are provided with a well defined transverse ridge 
following the long diameter of the joints, with fossz at both sides, and 
surrounded by a marginal reticulation. The ridges follow the twist of the 
stem downward, admitting motion in all directions. In these families there 
seems to have been a sort of rudimentary articulation between the suc- 
cessive joints, while in the other families there was only a loose sutural 
union. 
As to the habits of Crinoids, very little is yet known, even of the recent 
ones. We know that in their pedunculate state the Comatule were fixed 
by means of a large plate, the so-called dorso-central ; and this led to the 
belief that all Stalked Crinoids were permanently attached in a somewhat 
similar manner. But this has never been satisfactorily proved, and, as we 
know now, is not always the case with the recent Pentacrinide. The distal 
end in most Palwocrinoidea tapers rapidly and uniformly to a point, and the 
terminal branches are given off from several joints, and not from a single 
