C. Wachsmuth—Structure of Paleozoic Crinoids. 183 
toids, and it seems to me highly probable that the consolidating 
plates are homologous with the partly hidden deltoid pieces of 
the latter. 
the Cyathocrinide. Macrostylocrinus is allied to Melocrinus, and 
has undoubtedly a similar summit structure. The same may 
be said of Schizocrinus and Dimerocrinus which are not at all 
related to Cyathoerinus. 
he genus Cyathocrinus was originally described by Professor 
Phillips and Mr. Austin as having a separate mouth and vent, 
which was considered by these authors and others to be its 
chief distinction from Potertocrinus: Accordingly, all species 
with a proboscis or solid dome, though otherwise agreeing 
with Cyathocrinus, were referred to Poterwocrinus or some allied 
exceedingly interesting, and throws light upon the summit 
structure of many genera. I shall herein refer frequently to 
ar & Worthen’s excellent figures, vol. v, Plate 1x, figs. 13 
and 14. 
Looking only at fig. 14, one would at first naturally suppose 
there must have been, during the life of the animal, tw dis- 
tinct openings in the vault. But on examining it more criti- 
cally and comparing it with fig. 13, it will be found that fig. 
14 represents simply the consolidating apparatus as figured by 
twoomer and Schultze in Oupressocrinus, placed here exactly as 
in that genus, and consisting of five large pieces, alternating 
With the upper edges of the first radial plates. ‘The plate of 
the anal side is larger than the others and forms the base of the 
Inner side of the proboscis. The five pieces which connect 
with each other laterally, extend inward for some distance, but 
hot so far as to meet in the center where there is a semi-circular 
or heart-shaped opening. Along the sutures, between the five 
