SORES Pa PM hres ee ee AN 
REPORT ON THE CRINOIDEA. 87 
the greater part of the interior of the cup, but not reaching down to the basals, is a 
large convoluted organ, which has a general resemblance to the shell of a Bulla. It is 
open at both ends, and its longer axis nearly coincides with that of the body of the 
Crinoid. Wachsmuth and Springer’ describe its wall as being “simple in all cases, very 
delicate, and constructed of an extremely fine filigree work, which generally in the fossil 
became thickly incrusted with siliceous matter on both sides.” Hall, who was the first to 
notice this organ, made no suggestions respecting its nature. Meek and Worthen supposed 
it to be a kind of framework supporting the coiled digestive tube ;? while Wachsmuth and 
Springer suggest that it might be “an extensive plexus of blood-vessels surrounding the 
ambulacral (!) canal;” and desiring that it “should receive a more appropriate name 
than any yet given,” they propose to call it the “‘ cesophageal network.”* 
That it supported some of the intervisceral blood-vessels I have very little doubt ; 
but there is no reason to suppose that it actually represents the vessels themselves, which 
would have passed through the meshes of its network (compare Pl. LVIL fig. 5). As 
a similar though less developed structure occurs in recent Crinoids, I see no reason to 
doubt the correctness of Meek and Worthen’s determination. 
Neither do I think Wachsmuth and Springer’s name a good one, for it implies that 
the structure in question was connected with the cesophacus, and not with the rest of the 
digestive tube. But as it is so large, relatively to the interior of the calyx, the remainder 
of the digestive apparatus must in that case have been quite small, which is improbable 
for many reasons. 
According to Meek and Worthen,* “its slightly dilated upper end seems to stand 
with its middle almost, but apparently not exactly, under the middle of the nearly 
central proboscis of the vault; while at the anterior side of its upper margin, and a little 
out from under the proboscis, it shows remains of a kind of thickened collar, which we 
found to be composed of minute calcareous pieces. From this there radiate five 
ambulacra, composed of the same kind of minute pieces as the collar itself.” 
The thick collar was the edge of the peristome with its more or less regular supporting 
plates as in any recent Crinoid. The mouth was placed within this peristomial space, and 
the greater part of the convoluted organ would thus have lain altogether behind it. The 
direction of its spiral is exactly the same as that of the digestive tube in Antedon or 
Pentacrinus, as may be seen by comparing Dr. Carpenter's figure of the latter’ (viewed 
from above) and the “inferior end view” of the convoluted organ given by Meek and 
Worthen.’ I believe that the gullet ran downwards and backwards as it does in 
Pentacrinus; and that the intestine, after following the convolutions of its support, 
turned upwards again to end in the long anal tube, the so-called “ proboscis.” 
1 Revision, part ii. p. 35. 2 Paleontology of Illinois, vol. v. p. 329. 
3 Revision, part ii. p. 35. 4 Paleontology of Illinois, vol. v. p. 331. 
5 Proc. Roy. Soc. Lond., vol. xxiv. pl. viii. fig. 1. § Paleontology of Illinois, vol. v. pl. ix. fig. 120. 
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