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Meek and Worthen on Paleozoic Crinoidea. OF 
removed than the others, we would remark that they do not 
present the prominent appearance, and uniformity of size and 
form, of the movable pieces composing what is often called the 
ovarian pyramid in the Cystids, but certainly have all the 
appearances of true fixed vault pieces, and scarcely project 
above the others surrounding them. Consequently we cannot 
believe it at all probable that this genus had a central mouth, 
opening directly through the vault; though its ambulacral 
canals evidently converged from the arm-bases to the middle of 
the vault, partly above the outer vault pieces, and under those 
composing the middle of the vault, That these furrows termi- 
nated at the entrance of the alimentary canal, under the middle 
of the vault, as those of Comatula converge "to the mouth, in 
the same central position, is highly probable ; and, as will be 
seen further on, we are much inclined to believe that the minute 
organisms upon which we are led, from analogy, to think these 
animals subsisted, were conveyed to the entrance of the alimen- 
tary canal alone the ambulacral furrows, without the agency 
of any proper mouth, opening directly through the vault. 
Hence we think it probable that the small tube, usually called 
the proboscis, situated near the posterior side of the ventral 
disc, rather corresponds to the tubular anal opening similarly 
situated i in Comatula Mediterranea. 
ur description of the vault of these species, it will be 
seen ee posictit considerable similarity to that of Crotalocrinus 
yugosus, excepting that in that genus, owing to its great num- 
ber of arms, the ambulacral furrows, or canals, bifurcate seve- 
ral times between the middle of the vault and the arm-bases, 
while in Crotalocrinus there is no lateral roi i so nor, appa- 
rently, even any visible Bare hy 4 judging by the figures we 
have seen, though we suspect it may have a small opening at 
the periphery of the ventral disc, on the posterior or anal side. 
In the group of depressed Platycrini for which Troost proposed 
the name Cupellecrinus we observe a somewhat similar vault, 
at least in some of the species ; also in Coccocrinus. In suc 
forms there would seem to be, as it were, an intermediate gra- 
dation — the modern Crinoids and the prevailing Paleo- 
zoic types, as has been pointed out by Mr. Billings. 
4. Convoluted support of the digestive sack, in the Actino- 
crinidee.—The presence of a large convoluted body, resembling 
in form the shell of a Bulla or Scaphander, within the body 
of several types of the Actinocrinide, was noticed by Prot. 
Hall [this Journal, volume xli, p. 261], in 1866, though he 
made no suggestions there in regard to the functions it peeks 
ably performed in the internal economy of the 
the second volume of the Illinois Geological Reports, published 
