118 C. Wachsmuth—Structure of Paleozoic Crinoids. 
main tubes and branches are constructed on their lower side of 
alternating plates, upon which on either side, a second row of 
cently, in which they are well preserved and in place. e 
condition of the specimen, as Meek & Worthen remark, leaves 
but little doubt, but that the tubes form through the arm-open- 
ings of the calyx a continuation of the arm furrows, In re- 
moving parts of the vault, I unfortunately broke the upper 
‘part of the fragile skeleton, but enough is preserved to prove 
that the five main tubes did not connect di 
sometimes closed underneath, particularly in very old speci- 
mens, thus forming regular ducts or tunnels. Their arrange- 
ment seems to be similar in all these Crinoids, no matter 
whether the species has a subcentral proboscis or merely 4 
lateral opening, they always diverge from a plane on the inner 
wall of the vault, in front of the anus, and branch to the arm 
ne. 
generally attached when I found them, but so much decayed, 
