126 CO. Wachsmuth—Structure of Paleozoie Orinoids. 
canal partly preserved in Ollacrinus tuberculosus Hall, in which 
it seems to have been composed of the same delicate network, 
but the organ consists here of a round canal which descends 
spirally, and contracting gradually, takes at the lower portion 
of the visceral cavity an upward direction. The upper part of 
the organ is unfortunately not preserved in this specimen. 
4, The anal aperture and the proboscis. 
The anus of Paleozoic Crinoids is placed always within one 
of the interradial series, which is generally wider than—and 
often constructed differently from—the others. The aperture 
is situated either in some part of the calyx itself, or at the top 
of along proboscis. It is a most remarkable fact that genera 
which evidently belong to the same group, even species, 
apparently of the same genus, for instance Strotocrinus, differ 
so widely in the construction of this organ. Some having 4 
long massive tube, reaching to several inches above the tips of 
their arms, while others are provided only with a plain lateral 
opening without any superstructure whatever. 
I do not speak at present of the inflated or balloon-shaped 
proboscis of Zeacrinus, Coeliacrinus, Poteriocrinus, Heterocrinus 
The 
homologized with the 
“We can only 
compare its lateral opening, which is generally placed low 
down near the arm-bases, with the anal aperture of species 12 | 
. “sag . is tube may have connect 
with the terminal intestine which I have described above, and 
