186 C. Wachsmuth—Structure of Paleozoie Crinoids. 
some of them as perfect in most of their parts as if dredged 
from the ocean, but only two specimens have been discovered 
in which the summit was preserved, and only a single Seaphio- 
crinus. That this could happen at a locality where even the 
finest tissues of the most delicate internal organs are preserved, 
is somewhat astonishing, but yet it can be accounted for by the 
fact that the pieces which cover the central opening, as also the 
‘small alternating plates forming the ambulacral canal, are very 
thin and that they rest but partly upon the consolidating 
eaten being thereby rendered insecure and liable to removal 
y any accident, even with very small force. Moreover the 
arms of the Oyathocrinide are generally attached, and the ven- 
tral dise thus hidden from view. In specimens in which the 
arms are destroyed, their destruction almost invariably involved 
that of the entire ventral side, and so delicate are these parts, 
that even when the arms are well preserved and so situated as 
to ex the dome, the plates are nearly always gone, or are 
found in a confused mass inside the calyx. 
I come now to another group in which on the basis of the 
summit structure, such apparently diverse forms are included 
that Iam under the necessity, very unwillingly, of making a 
name for it. It includes the families Actinocrinide, Platycrin- 
ide, Rhodocrinide, Melocrinide, and the genera Schizocrinus, 
ymerocrinus and Macrostylocrinus, which Roemer has ranged 
ome the Cyathocrinide, and I call it provisionally the Spher- 
oide, from the form of the calyx which is generally somewhat 
spherical. This large group, embracing over one hundred gen- 
era and ranging from the base of the Silurian to the top of the 
ubcarboniferous, is capable of accurate definition, is easily 
distinguished, and fortunately the summit is very commonly 
found well preserved in most of the genera. 
