274 The American Geologist. Novemher, it;99 
the plates which in such a reconstruction would fill the in- 
terval enclosed by them. No such plates are found, nor does 
the proximal end of the stem fill such a position. It overlaps 
the infrabasals, not entering its calyx wall. Again, none of 
the five sutural lines coincide with any of the six sutures of 
the infrabasals, not even with the obsolete one. This is as 
would be expected. If the stem of Strophocrinus were re- 
stored, quite evidently we should find it with five sutural lines 
running from top to bottom. It is a flexible structure. Su- 
tures of the calyx on the contrary alternate, forming a rigid 
structure. A stem made up of hexagonal plates, as Neumayr 
thought the primitive stem to be, would, if close jointed, be 
rigid. Early crinoid stems are flexible, jointed structures, and 
the same type commonly occurs among cystids. If these were 
derived from an inflexible stem or extension from 
the cystidean body wall, the transition to the jointed 
structure would be first vertically compressed hexa- 
gonal alternating plates, second, quadrangular plates in circles, 
forming segments, third, solid rings; which three stages occur 
among unidentified stems at this locality. If, then, the trans- 
verse sections of the stems of Cystoidea ?,nd Crinoidea are 
consequent to the development of flexibility, the stem's dis- 
tinctness in symmetry and in demarcation from the calyx may 
be due to that alone. A primitive calyx with more or less than 
five infra])asals might indifferently attach to a pentameral 
stem, and as long as the sutures do not correspond between 
calyx. and stem the attachment would be firm. 
The associated basal expansions are also instructive. They 
resemble the one ascribed to Glyptocrinus from the Cincin- 
nati group, figured and described by Wachsmuth and Springer 
in "Crinoidea Camarata." The periphery is, however, circular 
when normal. The structure of the base or ''dorsocentral" of 
Barycrinus, described by them, applies well to this one : "The 
middle part of the truncated lower face is perfectly flat, and 
there are no traces shown of an axial canal. But in an out- 
ward direction we find grouped around a closed centre numer- 
ous small canals connecting with the interior. These canals 
form upon the surface well defined ramifying grooves which 
pass out to the periphery and seem to communicate with the 
surrounding water," op. cit. p. 47. This description applies 
