26 Meek and Worthen on Paleozoic Crinoidea. 
—the one on the anal side being larger than the others, and 
forming the base of the inner side of the proboscis. These five 
ct 8g connect with each other laterally, and extend inward 
istance, but not so far as to meet at the center, where 
‘hae; is a subsemicircular opening, nearly as large as ‘that in 
the remaining base of the proboscis. Along each of the sutures 
between the five vault pieces mentioned, a comparatively large 
furrow extends inward from each arm-base to the central open- 
ing. These we regard as continuations of the ambulacral fur- 
rows from the arms, though there is also a minute opening at 
each arm-base, passing directly downward into the cavity of 
the body, which was probably for the passage of the arm-mus- 
cle 
cee at this specimen alone, one would naturally suppose 
that there must have been, during the life of the animal, two dis- 
tinct ne in the vault, as appears to be the case in the speci- 
nof C. planus Miller, figured by Prof. Phillips and Mr, Aus- 
tin. But on examining the specimen of C. Iowensis mentioned 
above, we find that it shows the base of the small lateral pro- 
boscis, with the five principal vault pieces alternating with the 
first radials (the one on the anal side being larger than the oth- 
ers), and the same ambulacral — extending inward -— 
the arm-bases, all exactly as in the C. malvaceus. But 
we find the central opening shdircb belly closed by several vault 
pieces, while the ambulacral furrows, extending inward from 
the arm-bases, pass in under these central pieces, and are them- 
selves occupied, or covered, by a double series of alternating, 
very minute pieces, hoch probably also extend on, all the way 
up the ambulacral furrows of the arms as marginal pieces. 
rom our examinations of these two specimens, which are 
the only examples of the genus we have seen, showing the 
jos se pieces, and seem to be typical forms of the genus in all 
respects, we are strongly inclined to think the specimen 
of C. planus, figured by Prof. Phillips and Mr. Austin, has had 
these central vault pieces removed by some accident. The fact 
that _ ieces in the specimen examined by us, in Mr. Wachs- 
muth’s collection, seem not to be deeply implanted between 
i = at surrounding pieces mentioned, but rather rest as 
ere, partly upon the narrow beveled points of the inner 
pit of the latter, between the ambulacral furrows, so as to al- 
low room for these furrows to pass under, would abe them 
less firm, and more liable to be removed by any accident, an 
may possibly account for their absence in the English specimen 
mention 
In regard to the pieces covering the central part of the vault, 
and which, from the way they are arranged for the ambulacral 
rows to. pass under them, were apparently more liable to be 
