C. Wachsmuth—Structure of Paleozoie Crinoids. 125 
The convolutions are directed outward from left to right, 
varying in number from two to four in different species. 
Judging from external appearance only, the convoluted walls 
of the organ appear as mere partitions leading to the inner 
chamber of a bulla-shaped body. This however. is not the 
act. Hxamining the so-called walls in some transverse sec- 
tions, I find them to be coiled, without touching each other at 
any point, and composed of two distinct partitions, placed side 
by side and closed at the edges, thus proving that the apparent 
more turns, while the inner one, winding in a spiral way around 
its Own axis, passed upward to near the center of the dome. 
ecimen of Actinocrinus in which the digestive organ is 
Apparently perfect, though showing the usual rough appearance, 
I succeeded in removing at one side the two upper convolutions, 
‘n such a manner that the detached parts can be replaced or 
lifted up for investigation. I had here an opportunity to 
examine the inner or more properly upper end of the ali- 
mentary canal (as distinguished from the outer end or terminal 
part). The top is unfortunately hidden below some inorganic 
matter, but enough can be seen to prove that it proceeded evi- 
dently from a place below the center of the dome. The organ, 
where it comes into view, is an elongated tube, which passing 
downward, widens first gradually to near the middle of the 
visceral cavity, then rapidly until it acquires the width of at 
least two-thirds of the entire length of the cavity. The upper 
end in descending spirally turns from right to left, but on 
oming wider curves sharply in the opposite direction and 
the convolutions are now directed from left to right. The outer 
end also tapering rapidly and forming a flattened tube, ascends 
the outside spirally from below all the way up to the top, and 
while the ma end communicated with the food-groove. _ 
Such, wit slight modifications, was probably the construction 
. the alimentary canal of all Actinocrinide, Pla tycrinide, ete., 
Ut not that of the genus Ollacrinus.* I found the alimentary 
Lone sured by Cumberland without generic or specific diagnosis or specific name, 
30% 1826, in the Appendix to Reliquie Conservate. eS 
9 20n.—Gilbertsocrinus Phillips, 1836, Geol. Yorkshire, Pl. II, p. 207. Gont- 
qiteroidocrinus Lyon & Casseday, Suppl. Geol. Rept., Iowa, p. 70. Zrematrocrinus 
Hlall, 1860, Suppl. Towa Geol. Rept., p. 70. a, : 
- Cumberland’s figure is perfectly correct and easily identified as Ollacrinus 
) calcaratus, his generic name “ Ollacrinus” must be retained accord- 
ing to the laws of nomenclature. 
