124 C. Wachsmuth—Structure of Paleozote Crinoids. 
thus forming a mere covering, we shall find the position of the 
circular organ perfectly harmonious with that of all other 
Kchinoderms. 
I have mentioned already that there exists in the arm-groove 
of Cyathocrinus, beneath the tube and at the bottom of the fur- 
r. Schultze, in his “ Monograph on the Echinoderms of the 
Eifel,” p. 17, gives a most excellent description of the arm-fur- 
row in OCupressocrinus. He found two sets of plates covering 
the furrow like a roof, and asserts, that the inner pieces could 
be turned back in the living animal. I had overlooked this 
in making out my descriptions, but it was pleasing and highly 
satisfactory to me to find that we both had arrived independ- 
furrow of Cupressoerinus is very similar to Cyathocrinus. In a 
section of the arm of this genus, I readily distinguished, by 
transmitted light, the food-groove, which has a narrow and dee 
outline, a canal on both sides of it, and I have but little doubt 
but that the arm-furrows were similarly constructed in a 
Paleozoic Crinoids. : 
3. The alimentary canal. 
k and Worthen publish in the Geological Report of 
convoluted body, resembling in outer form and outline the 
shell of a Bulla, with a longer vertical axis, and open at both 
ends. The upper end is placed below the center of the ventral 
ue cases it is subcylindrical and slightly truncate at bot 
ends. 
_ pieces or bars with intervening meshes, but its delicate texture 
1s but seldom observed, owing to the piece of incrustations 
of calcareous or siliceous matter which {ill up the meshes, ap 
give to the structure a rather dense appearance. * 
_ * To these shisha which = evidently deposits from the water, we oWe 
in a great measure the preservation of these delicate organs, and as they are com- 
ara thicker in adult specimens, they seem to have accumulated already 
—— life of the Crinoids, and may have caused in many 
