222 Cincinnati Society of Natural History. 
clusion. To correct such erroneous views. and to settle the question, 
at least with regard to this genus, I bee leave to call the attention of 
the reader to the illustrations of this species on Plate XI., as well as 
to what is here said. 
The excurrent opening is situated subcentrally upon the upper face 
of the vault. It appears as a subcircular, depressed conical elevation, 
composed of plates, imbricating toward the center, while a few of the 
surrounding plates have rather long spines, inclined toward the 
central part of the orifice. One specimen showing the lower side of 
the vault, indicates the extension of a sack like form into the cavity 
below this excurrent opening, and it may be, that there was such con- 
nection with the ambulacral furrows, that this opening needed such 
support, but as I am unable to distinguish the plates, in this apparent 
extension, I do not assert the existence of it as part of the structure 
of the crinoid. Figure le, on Plate XI., is magnified six diameters, the 
upper part of the illustration reaches the larger plates of the central 
part of the vault, while the side spinous plates are those following the 
waves toward the arm furrows. 
It being definitely settled that the pinnules do not cover the arm 
furrows, the question very naturally suggests itself as to whether or 
not they had any connection with them. If they were perforated they 
had communication with the arm furrows, and if they were not per- 
forated, they did not. Prepared microscopic sections would, probably, 
settle this question, and I will let it remain unanswered until some 
one prepares such sections. 
The surface of the calyx, in this species, is ornamented with strong 
radiating ridges, from the center of each plate, in the lower half, so as. 
to form triangular depressed areas, which become less conspicuous in 
the middle part, and fade away in the intertertiary areas. 
Found in the middle part of the Hudson River Group. 
GLYPTOCRINUS DYERI ( Hall). 
G. dyert is distinguished from G. decadactylus by having a bowl- 
shaped calyx below the secondary radials, and rather less prominent 
ridges; by having 12 to 15 by 10 secondary radials, instead of 2 by 
10, and consequently an increased number of intersecondary plates; 
the interradial and intersecondary radial areas are not so much de- 
pressed; there are no tertiary or intertertiary areas; the arms bifur- 
cate and become free at the top of the vault. Prof.. Meek said, the 
second and fourth secondary radials— 
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at 
4 
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