22 Meek and Worthen on Paleozoic Crinoidea. 
@ little at first above, so as not to pass directly under the pro- 
boscis. These ambulacra, although passing along obscure fur- 
rows in the under side of the vault, which are deepest near the 
arm-openings, are not 7” contact with the vault, or visibly con- 
nected with any other parts than the top of the convoluted 
digestive sack, and the outer walls at the Bein apes uie Hach 
of their subdivisions can be traced into an arm-openi 
is very probable that they continued on out. the ‘aitulaccal 
furrows of the arms and tentacula. At one point in one of 
these ambulacral canals, beneath the vault, some evidences of 
the remains of two rows of minute pieces were observed alter- _ 
nating with the upper edges of those composing the under side 
of these canals, and thus apparently covering them over, The 
condition of the parts is such however, as scarcely to warrant 
the assertion that this was really ape case, though we are much 
inclined to think it was. If so, these canals must have been, 
at least under the vault, hollow tubes, formed of two rows of 
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and we can but think it probable, that the extremely rare com- 
bination of circumstances that brought them to light in this 
on the outside the ventral disc in Comatula, is clearly evident. 
e presence of furrows radiating from the central region of 
the under side of the vault to the arm-openings, in various 
types of paleozoic Crinoids, must have been frequently ob- 
sre oe ty all zie have had an opportunity to examine the inner 
part, Messrs. de Koninck and Lehon figure a 
< of the Sault of Actinocrinus stellaris, in their valuable 
mtg, 4f., sowing these furrows, which they seem to have 
iferous Crinoids is ee to have pom furrows more or less 
defined, either from specimens showing this inner surface, oF 
from natural casts of the same. In some instances they are 
very strongly defined from the central region outward to the 
arm-bases, to each of which they send a branch. In Actinocri- 
nus ornatus Hall, for instance, they are generally so strongly 
defined as to raise the thin vault into strong radiating ridges, 
